1、备份 /etc/yum.repos.d/CentOS-Base.repo

cp /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.bak

2、编译 vim /etc/yum.repos.d/CentOS-Base.repo ，写入

[base]

name=CentOS-$releasever - Base

baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos-vault/7.9.2009/os/$basearch/

gpgcheck=1

gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

enabled=1

[updates]

name=CentOS-$releasever - Updates

baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos-vault/7.9.2009/updates/$basearch/

gpgcheck=1

gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

enabled=1

[extras]

name=CentOS-$releasever - Extras

baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos-vault/7.9.2009/extras/$basearch/

gpgcheck=1

gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

enabled=1

[centosplus]

name=CentOS-$releasever - Plus

baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos-vault/7.9.2009/centosplus/$basearch/

gpgcheck=1

gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

enabled=0

3、更新缓存

rm -rf /var/cache/yum

yum clean all

yum makecache

如果是centos其它版本怎么办？

访问https://mirrors.tuna.tsinghua.edu.cn/centos-vault/

查找对应的版本！