备份本地源

1

mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup

配置CentOS7(aliyun) yum源

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wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo

把$releasever替换为7

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sed -i  's/$releasever/7/g'  /etc/yum.repos.d/CentOS-Base.repo