In previous versions of WordPress 2.9, the intergration is easy to do:

<?php if ( is_singular() ) echo '<link rel="canonical" href="' . get_permalink() . '" />'; ?>

Putting it in the header.php of the theme is the easiest way to have the link-tag in the head of your frontend.

Since WordPress 2.9 it won't be necessary because WordPress set with the help of the default filter, see wp-includes/default-filters.php, the link-tag to the hook wp_head.

add_action( 'wp_head', 'rel_canonical' );

Thereby it calls the function rel_canonical(), which simply writes the HTML and passes the link of the article. Alternatively you can disable the filter and you can use it yourself.

remove_action( 'wp_head', 'rel_canonical' ); // to delete in head

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You can test this fully functional version of wpSEO for 10 days. This Plugin is free to use for every personal blog, you just have to request a free license key here. Commercial projects or ad-supported blogs have to purchase an affordable license key for this Plugin after the 10 days trial period.

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Click on the image above to see all options. If you have any questions don't hesitate to contact us.

Some of the features are:

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• Importing and exporting your settings
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• Absolutely no additional database queries
• Very fast execution
• No need to adjust any templates
• An included XML file with recommended options
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• Uninstall function
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Enjoy wpSEO for WordPress!