WordPress设置栏没有ICP备案号的解决方案

问题：

仪表盘里【设置-常规】，滑倒最下面的“ICP备案号”在5.0.0及以后的wordpress版本里没有显示。

解决方案：

1. 文件wp-content/languages/zh_CN.php缺失，内容在后面附上。
2. 在wp-config.php中添加define('WP_ZH_CN_ICP_NUM', true);
3. 在自己使用的主题的页脚文件footer.php里合适的位置加上
   <a href="http://beian.miit.gov.cn" rel="external nofollow noopener noreferrer" target="_blank"><?php echo get_option( 'zh_cn_l10n_icp_num' );?></a>
4. 刷新仪表盘，【设置-常规】里出现了ICP备案号，填入刷新网页即可。

附上zh_CN.php:

<?php
/**
 * WordPress China Localization Patches Collection
 */

/**
 * Legacy database options cleanup
 *
 * Cleanup of all options that were introduced pre-3.4.
 * To save time, this function is only to be called on admin pages.
 *
 * @since 3.4.0
 */
function zh_cn_l10n_legacy_option_cleanup() {
    // 3.3 series
    delete_site_option( 'zh_cn_l10n_preference_patches' );

    // 3.0.5, 3.1 series, 3.2 series
    delete_site_option( 'zh_cn_language_pack_enable_chinese_fake_oembed' );

    // 3.0.1, 3.0.2, 3.0.3, 3.0.4
    delete_site_option( 'zh_cn_language_pack_options_version' );
    delete_site_option( 'zh_cn_language_pack_enable_backend_style_modifications' );

    // awkward ones...
    delete_site_option( 'zh_cn_language_pack_enable_icpip_num_show' );
    delete_site_option( 'zh_cn_language_pack_icpip_num' );
    delete_site_option( 'zh_cn_language_pack_is_configured' );

}
add_action( 'admin_init', 'zh_cn_l10n_legacy_option_cleanup' );

/**
 * ICP license number
 *
 * For compliance with the Telecommunications Regulations. Can be turned off
 * in wp-config.php.
 *
 * @since 3.7.0
 */
function zh_cn_l10n_settings_init() {
    if ( defined( 'WP_ZH_CN_ICP_NUM' ) && WP_ZH_CN_ICP_NUM ) {
        add_settings_field( 'zh_cn_l10n_icp_num',
            'ICP备案号',
            'zh_cn_l10n_icp_num_callback',
            'general' );
        register_setting( 'general', 'zh_cn_l10n_icp_num' );
    }
}

add_action( 'admin_init', 'zh_cn_l10n_settings_init' );

function zh_cn_l10n_icp_num_callback() {
    echo '<input name="zh_cn_l10n_icp_num" type="text" ' .
        'id="zh_cn_l10n_icp_num" value="' .
        esc_attr( get_option( 'zh_cn_l10n_icp_num' ) ) .
        '" class="regluar-text ltr" />' .
        '<p class="description">仅对WordPress自带主题有效。</p>';
}

function zh_cn_l10n_icp_num( $content ) {
    if ( defined( 'WP_ZH_CN_ICP_NUM' ) && WP_ZH_CN_ICP_NUM &&
        get_option( 'zh_cn_l10n_icp_num' ) ) {
        echo '<a href="http://beian.miit.gov.cn/" rel="nofollow" ' .
            'title="工业和信息化部ICP/IP地址/域名信息备案管理系统">' .
            esc_attr( get_option( 'zh_cn_l10n_icp_num' ) ) .
            "</a>\n";
    }
}

add_action( 'twentyten_credits', 'zh_cn_l10n_icp_num' );
add_action( 'twentyeleven_credits', 'zh_cn_l10n_icp_num' );
add_action( 'twentytwelve_credits', 'zh_cn_l10n_icp_num' );
add_action( 'twentythirteen_credits', 'zh_cn_l10n_icp_num' );
add_action( 'twentyfourteen_credits', 'zh_cn_l10n_icp_num' );
add_action( 'twentyfifteen_credits', 'zh_cn_l10n_icp_num' );
add_action( 'twentysixteen_credits', 'zh_cn_l10n_icp_num' );
add_action( 'twentyseventeen_credits', 'zh_cn_l10n_icp_num' );
?>