Loading mirror speeds from cached hostfile Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=7&arch=x86_64&repo=os&infra=stock error was 14: curl#6 - "Could not resolve host: mirrorlist.centos.org; 未知的错误" One of the configured repositories failed (未知), and yum doesn't have enough cached data to continue. At this point the only safe thing yum can do is fail. There are a few ways to work "fix" this: 1. Contact the upstream for the repository and get them to fix the problem. 2. Reconfigure the baseurl/etc. for the repository, to point to a working upstream. This is most often useful if you are using a newer distribution release than is supported by the repository (and the packages for the previous distribution release still work). 3. Run the command with the repository temporarily disabled yum --disablerepo=<repoid> ... 4. Disable the repository permanently, so yum won't use it by default. Yum will then just ignore the repository until you permanently enable it again or use --enablerepo for temporary usage: yum-config-manager --disable <repoid> or subscription-manager repos --disable=<repoid> 5. Configure the failing repository to be skipped, if it is unavailable. Note that yum will try to contact the repo. when it runs most commands, so will have to try and fail each time (and thus. yum will be be much slower). If it is a very temporary problem though, this is often a nice compromise: yum-config-manager --save --setopt=<repoid>.skip_if_unavailable=true Cannot find a valid baseurl for repo: base/7/x86_64

这个错误提示是因为 yum 在安装软件包时无法从 CentOS 官方镜像站点获取软件包列表。造成这个问题的原因可能是因为您的网络连接存在问题，或者是因为 CentOS 官方镜像站点出现了故障。您可以尝试以下几种方法来解决这个问题：

1. 检查网络连接是否正常。可以尝试使用 ping 命令测试 CentOS 官方镜像站点是否可以正常访问。例如：`ping mirrorlist.centos.org`。

2. 检查 DNS 配置是否正确。如果您使用的是静态 IP 地址，请确保已正确配置 DNS 服务器地址。如果您使用的是 DHCP，可能需要等待 DHCP 分配器更新 DNS 配置。

3. 检查 /etc/yum.repos.d 目录下的 CentOS-Base.repo 文件是否存在，并检查文件内容是否正确。您可以备份该文件，并将其替换为以下内容：

   [base]
   name=CentOS-$releasever - Base
   baseurl=http://vault.centos.org/centos/$releasever/os/$basearch/
   gpgcheck=1
   gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
   enabled=1

4. 尝试清除 yum 缓存并重建缓存。可以使用以下命令清除 yum 缓存：

   sudo yum clean all

然后使用以下命令重新生成缓存：

   sudo yum makecache

5. 如果以上方法都无法解决问题，可以考虑使用其它镜像站点，或者等待 CentOS 官方镜像站点恢复正常。可以编辑 /etc/yum.repos.d/CentOS-Base.repo 文件，将 baseurl 设置为其它可用的镜像站点。例如：

   [base]
   name=CentOS-$releasever - Base
   baseurl=http://mirror.centos.org/centos/$releasever/os/$basearch/
   gpgcheck=1
   gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
   enabled=1

修改完成后，重新运行 yum 命令即可。