错误信息：

    1. Downloading packages:
    2. 警告：/var/cache/yum/x86_64/7/nginx-stable/packages/nginx-1.18.0-2.el7.ngx.x86_64.rpm: 头V4 RSA/SHA1 Signature, 密钥 ID 7bd9bf62: NOKEY
    3. 从 https://nginx.org/keys/nginx_signing.key 检索密钥
    4. 获取 GPG 密钥失败：[Errno 14] curl#60 - "Peer's Certificate has expired."

    解决办法：

    1. 1、cat/etc/yum.repo.d/nginx.repo 
    2. 找到 gpgkey=https://nginx.org/keys/nginx_signing.key进行下载
    3. 2、wget https://nginx.org/keys/nginx_signing.key --no-check-certificate
    4. rpm  --import  nginx_signing.key
    1. [root@web00 ~]# wget https://nginx.org/keys/nginx_signing.key --no-check-certificate
    2. --2020-10-28 01:26:39--  https://nginx.org/keys/nginx_signing.key
    3. 正在解析主机 nginx.org (nginx.org)... 52.58.199.22, 3.125.197.172, 2a05:d014:edb:5704::6, ...
    4. 正在连接 nginx.org (nginx.org)|52.58.199.22|:443... 已连接。
    5. 警告: 无法验证 nginx.org 的由 “/C=US/O=Let's Encrypt/CN=Let's Encrypt Authority X3” 颁发的证书:
    6.   颁发的证书还未生效。
    7. 已发出 HTTP 请求，正在等待回应... 200 OK
    8. 长度：1561 (1.5K) [application/octet-stream]
    9. 正在保存至: “nginx_signing.key”
    11. 100%[=====================>] 1,561       --.-K/s 用时 0s      
    13. 2020-10-28 01:26:41 (216 MB/s) - 已保存 “nginx_signing.key” [1561/1561])
    15. [root@web00 ~]# rpm --import nginx_signing.key