异常表现

CentOS-8 - AppStream
Failed to download metadata for repo 'AppStream'
Error: Failed to download metadata for repo 'AppStream'

处理脚本

cd /etc/yum.repos.d/
sudo sed -i 's/mirrorlist/#mirrorlist/g' /etc/yum.repos.d/CentOS-*
sudo sed -i 's|#baseurl=http://mirror.centos.org|baseurl=http://vault.centos.org|g' /etc/yum.repos.d/CentOS-*
sudo yum update -y

wget 'http://mirror.centos.org/centos/8-stream/BaseOS/x86_64/os/Packages/centos-gpg-keys-8-3.el8.noarch.rpm'
sudo rpm -i 'centos-gpg-keys-8-3.el8.noarch.rpm'
dnf --disablerepo '*' --enablerepo=extras swap centos-linux-repos centos-stream-repos
dnf distro-sync