CentOS
解決"Failed to download metadata for repo appstream"問題
參考資訊：
1. failed-metadata-repo-appstream-centos-8
問題如下：
Failed to set locale, defaulting to C.UTF-8 CentOS Linux 8 - AppStream Error: Failed to download metadata for repo 'appstream': Cannot prepare internal mirrorlist: No URLs in mirrorlist
解法如下：
# cd /etc/yum.repos.d/ # sed -i 's/mirrorlist/#mirrorlist/g' /etc/yum.repos.d/CentOS-* # sed -i 's|#baseurl=http://mirror.centos.org|baseurl=http://vault.centos.org|g' /etc/yum.repos.d/CentOS-* # yum update -y