解决：Cannot find a valid baseurl for repo: base/7/x86_64

传送门

repo_file=/etc/yum.repos.d/CentOS-Base.repo
cp ${repo_file} ~/CentOS-Base.repo.backup
sudo sed -i s/#baseurl/baseurl/ ${repo_file}
sudo sed -i s/mirrorlist.centos.org/vault.centos.org/ ${repo_file}
sudo sed -i s/mirror.centos.org/vault.centos.org/ ${repo_file}
sudo yum clean all