WordPress后台直接显示文章、页面、分类、标签和用户等ID号

有时我们需要查看某篇文章或者分类的 ID，需要将鼠标放在文章或者分类名称上，然后查看浏览器状态栏上链接中的数字才能获得 ID 号，不够直观，可以将下面的代码添加到当前主题 functions.php 文件中，之后会在后台文章、分类等列表后面直接显示 ID 号：

// Prepend the new column to the columns array
    function ssid_column($cols) {
        $cols['ssid'] = 'ID';
        return $cols;
    }
    // Echo the ID for the new column
    function ssid_value($column_name, $id) {
        if ($column_name == 'ssid')
            echo $id;
    }
    function ssid_return_value($value, $column_name, $id) {
        if ($column_name == 'ssid')
            $value = $id;
        return $value;
    }
    // Output CSS for width of new column
    function ssid_css() {
    ?>
    <style type="text/css">
        #ssid { width: 50px; } /* Simply Show IDs */
    </style>
    <?php
    }
    // Actions/Filters for various tables and the css output
    function ssid_add() {
        add_action('admin_head', 'ssid_css');
        add_filter('manage_posts_columns', 'ssid_column');
        add_action('manage_posts_custom_column', 'ssid_value', 10, 2);
        add_filter('manage_pages_columns', 'ssid_column');
        add_action('manage_pages_custom_column', 'ssid_value', 10, 2);
        add_filter('manage_media_columns', 'ssid_column');
        add_action('manage_media_custom_column', 'ssid_value', 10, 2);
        add_filter('manage_link-manager_columns', 'ssid_column');
        add_action('manage_link_custom_column', 'ssid_value', 10, 2);
        add_action('manage_edit-link-categories_columns', 'ssid_column');
        add_filter('manage_link_categories_custom_column', 'ssid_return_value', 10, 3);
        foreach ( get_taxonomies() as $taxonomy ) {
            add_action("manage_edit-${taxonomy}_columns", 'ssid_column');
            add_filter("manage_${taxonomy}_custom_column", 'ssid_return_value', 10, 3);
        }
        add_action('manage_users_columns', 'ssid_column');
        add_filter('manage_users_custom_column', 'ssid_return_value', 10, 3);
        add_action('manage_edit-comments_columns', 'ssid_column');
        add_action('manage_comments_custom_column', 'ssid_value', 10, 2);
    }
    add_action('admin_init', 'ssid_add');