- 详细问题：
[constade@localhost yum.repos.d]$ sudo yum update CentOS Linux 8 - AppStream 0.0 B/s | 0 B 00:00 Errors during downloading metadata for repository 'appstream': - Curl error (6): Couldn't resolve host name for http://mirror.cloud.aliyuncs.com/centos-vault/8.5.2111/AppStream/x86_64/os/repodata/repomd.xml [Could not resolve host: mirror.cloud.aliyuncs.com] 错误：为仓库 'appstream' 下载元数据失败 : Cannot download repomd.xml: Cannot download repodata/repomd.xml: All mirrors were tried
- 问题原因：
CentOS8操作系统版本生命周期结束，Linux社区不再维护，如需过渡使用，则需要换源。
- 解决办法
备份/etc/repos.d/里的所有文件
cd /etc/repos.d/ sudo rename '.repo' '.repo.bak' /etc/yum.repos.d/*.repo
下载最新的repo文件,从阿里云下载
sudo wget https://mirrors.aliyun.com/repo/Centos-vault-8.5.2111.repo -O /etc/yum.repos.d/Centos-vault-8.5.2111.repo sudo wget https://mirrors.aliyun.com/repo/epel-archive-8.repo -O /etc/yum.repos.d/epel-archive-8.repo
- 替换源链接
sed -i 's/mirrors.cloud.aliyuncs.com/mirrors.aliyun.com/g' /etc/yum.repos.d/Centos-vault-8.5.2111.repo sed -i 's/mirrors.cloud.aliyuncs.com/mirrors.aliyun.com/g' /etc/yum.repos.d/epel-archive-8.repo
- 清除并更新缓存
yum clean all && yum makecache
- 检验成果
sudo yum update
