cat_rows
cat_rows is a filter that filters the display of the categories lists under Manage -> Categories and Blogroll -> Categories. To filter individual rows instead of the whole list, use the cat_row filter.
Context:
File: wp-admin/includes/template.php$output = ob_get_contents();
ob_end_clean();
$output = apply_filters('cat_rows', $output);
echo $output;
Context:
File: wp-admin/edit-link-categories.phpforeach ( $categories as $category ) {
$category = sanitize_term($category, 'link_category', 'display');
$output .= link_cat_row($category);
}
$output = apply_filters('cat_rows', $output);
echo $output;
This hook is a filter which means that information is passed through it, and then used by WordPress. Your function needs to accept that information, and return it. Using add_filter('cat_rows', 'your_function'); helps you to remember this distinction. When you are passing an ID, it is assumed that you will return the ID as it was given to you. With filters that pass strings or arrays, you may manipulate the information before passing it along.