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Perl: the Markov chain saw


by root (Scribe)
on Dec 23, 1999 at 00:50 UTC ( #1166=perlfunc: print w/replies, xml ) Need Help??


See the current Perl documentation for CGI::Cookie.

Here is our local, out-dated (pre-5.6) version:

CGI::Cookie - Interface to Netscape Cookies

    use CGI qw/:standard/;
    use CGI::Cookie;

    # Create new cookies and send them
    $cookie1 = new CGI::Cookie(-name=>'ID',-value=>123456);
    $cookie2 = new CGI::Cookie(-name=>'preferences',


CGI::Cookie is an interface to Netscape (HTTP/1.1) cookies, an innovation that allows Web servers to store persistent information on the browser's side of the connection. Although CGI::Cookie is intended to be used in conjunction with (and is in fact used by it internally), you can use this module independently.

For full information on cookies see


CGI::Cookie is object oriented. Each cookie object has a name and a value. The name is any scalar value. The value is any scalar or array value (associative arrays are also allowed). Cookies also have several optional attributes, including:

  1. expiration date

    The expiration date tells the browser how long to hang on to the cookie. If the cookie specifies an expiration date in the future, the browser will store the cookie information in a disk file and return it to the server every time the user reconnects (until the expiration date is reached). If the cookie species an expiration date in the past, the browser will remove the cookie from the disk file. If the expiration date is not specified, the cookie will persist only until the user quits the browser.

  2. 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 ``'', then Netscape will return the cookie to Web servers running on any of the machines ``'', ``'', ``'', 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. 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/'', ``/cgi-bin/'', and ``/cgi-bin/customer_service/'', but not to the script ``/cgi-private/''. By default, path is set to ``/'', which causes the cookie to be sent to any CGI script on your site.

  4. 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.

Creating New Cookies

        $c = new CGI::Cookie(-name    =>  'foo',
                             -value   =>  'bar',
                             -expires =>  '+3M',
                             -domain  =>  '',
                             -path    =>  '/cgi-bin/database'
                             -secure  =>  1

Create cookies from scratch with the new method. The -name and -value parameters are required. The name must be a scalar value. The value can be a scalar, an array reference, or a hash reference. (At some point in the future cookies will support one of the Perl object serialization protocols for full generality).

-expires accepts any of the relative or absolute date formats recognized by, for example ``+3M'' for three months in the future. See's documentation for details.

-domain points to a domain name or to a fully qualified host name. If not specified, the cookie will be returned only to the Web server that created it.

-path points to a partial URL on the current server. The cookie will be returned to all URLs beginning with the specified path. If not specified, it defaults to '/', which returns the cookie to all pages at your site.

-secure if set to a true value instructs the browser to return the cookie only when a cryptographic protocol is in use.

Sending the Cookie to the Browser

Within a CGI script you can send a cookie to the browser by creating one or more Set-Cookie: fields in the HTTP header. Here is a typical sequence:

  my $c = new CGI::Cookie(-name    =>  'foo',
                          -value   =>  ['bar','baz'],
                          -expires =>  '+3M');

  print "Set-Cookie: $c\n";
  print "Content-Type: text/html\n\n";

To send more than one cookie, create several Set-Cookie: fields. Alternatively, you may concatenate the cookies together with ``; '' and send them in one field.

If you are using, you send cookies by providing a -cookie argument to the header() method:

  print header(-cookie=>$c);

Mod_perl users can set cookies using the request object's header_out() method:


Internally, Cookie overloads the ``'' operator to call its as_string() method when incorporated into the HTTP header. as_string() turns the Cookie's internal representation into an RFC-compliant text representation. You may call as_string() yourself if you prefer:

  print "Set-Cookie: ",$c->as_string,"\n";

Recovering Previous Cookies

        %cookies = fetch CGI::Cookie;

fetch returns an associative array consisting of all cookies returned by the browser. The keys of the array are the cookie names. You can iterate through the cookies this way:

        %cookies = fetch CGI::Cookie;
        foreach (keys %cookies) {

In a scalar context, fetch() returns a hash reference, which may be more efficient if you are manipulating multiple cookies. uses the URL escaping methods to save and restore reserved characters in its cookies. If you are trying to retrieve a cookie set by a foreign server, this escaping method may trip you up. Use raw_fetch() instead, which has the same semantics as fetch(), but performs no unescaping.

You may also retrieve cookies that were stored in some external form using the parse() class method:

       $COOKIES = `cat /usr/tmp/Cookie_stash`;
       %cookies = parse CGI::Cookie($COOKIES);

Manipulating Cookies

Cookie objects have a series of accessor methods to get and set cookie attributes. Each accessor has a similar syntax. Called without arguments, the accessor returns the current value of the attribute. Called with an argument, the accessor changes the attribute and returns its new value.


Get or set the cookie's name. Example:

        $name = $c->name;
        $new_name = $c->name('fred');

Get or set the cookie's value. Example:

        $value = $c->value;
        @new_value = $c->value(['a','b','c','d']);

value() is context sensitive. In an array context it will return the current value of the cookie as an array. In a scalar context it will return the first value of a multivalued cookie.


Get or set the cookie's domain.


Get or set the cookie's path.


Get or set the cookie's expiration time.


be used and modified freely, but I do request that this copyright notice remain attached to the file. You may modify this module as you wish, but if you redistribute a modified version, please attach a note listing the modifications you have made.

Address bug reports and comments to:


This section intentionally left blank.


Carp, CGI =cut

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