curl#6 - "Could not resolve host: mirrorlist.centos.org; Unknown error" One of the configured repositories failed (Unknown), 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

这个错误提示表明 yum 无法连接到 CentOS 软件仓库，可能是由于网络连接问题、DNS 配置错误或者 CentOS 软件仓库不可用等原因导致的。

你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。可以使用 ping 命令来测试是否可以连接 CentOS 软件仓库。

2. 检查 DNS 配置是否正确。可以使用 nslookup 命令来测试是否可以解析 CentOS 软件仓库的域名。

3. 确认 CentOS 软件仓库是否可用。可以在浏览器中访问 CentOS 软件仓库的网站来确认是否可以连接。

4. 临时禁用该软件仓库。可以运行以下命令来禁用该软件仓库，然后重新运行 yum 命令：

yum --disablerepo=base/7/x86_64 <command>

5. 永久禁用该软件仓库。可以运行以下命令来永久禁用该软件仓库，然后重新运行 yum 命令：

yum-config-manager --disable base/7/x86_64

6. 更换软件仓库源。可以编辑 /etc/yum.repos.d/CentOS-Base.repo 文件，将 baseurl 和 mirrorlist 修改为可用的软件仓库源，保存后重新运行 yum 命令。