Using Cookies (Perl Cookbook, 2nd Edition)

20.14. Using Cookies

20.14.1. Problem

You want to fetch web pages, but the server is using cookies to track you. For example, some sites use a cookie to remember that you've authenticated. If you don't send the right cookie, you'll never get past the login screen.

20.14.2. Solution

Let LWP::UserAgent handle cookies for you. You can enable cookies for just this program run with:

$ua->cookie_jar({  });

Or instead store cookies in a file between invocations with:

$ua->cookie_jar({ file => "$ENV{HOME}/.cookies" });

20.14.3. Discussion

The default behavior of LWP::UserAgent is never to send a Cookie: header, even when the server offers cookies in a response. To keep track of cookies LWP::UserAgent receives and send them when appropriate, provide the user agent object with a special "cookie jar" object to hold the cookies: an HTTP::Cookies object.

Pass the cookie_jar method either an HTTP::Cookies object to use that object as the cookie jar, or else a hash reference whose contents go into a new HTTP::Cookies object.

Without parameters, an HTTP::Cookies object keeps cookies in memory, so they're no longer available once your program exits. The file parameter in the cookie_jar method call specifies a filename to use for initializing the cookie jar and for saving updated or new cookies. This is how you give cookies a shelf life beyond a single run of your program.

To disable cookies, call cookie_jar with no parameters:

$ua->cookie_jar( );

20.14.4. See Also

The documentation for the CPAN modules LWP::UserAgent and HTTP::Cookie