全部步骤

cd /etc/yum.repos.d
mkdir backup
mv *.repo backup/
#这里将下方的vault源选一个添加到/etc/yum.repos.d/
yum clean all
yum makecache

官方源

cat > CentOS-Vault.repo << 'EOF'
[base]
name=CentOS-\$releasever - Base - vault.centos.org
baseurl=http://vault.centos.org/7.9.2009/os/\$basearch/
gpgcheck=1
gpgkey=http://vault.centos.org/RPM-GPG-KEY-CentOS-7

[updates]
name=CentOS-\$releasever - Updates - vault.centos.org
baseurl=http://vault.centos.org/7.9.2009/updates/\$basearch/
gpgcheck=1
gpgkey=http://vault.centos.org/RPM-GPG-KEY-CentOS-7

[extras]
name=CentOS-\$releasever - Extras - vault.centos.org
baseurl=http://vault.centos.org/7.9.2009/extras/\$basearch/
gpgcheck=1
gpgkey=http://vault.centos.org/RPM-GPG-KEY-CentOS-7
EOF

阿里源

cat > CentOS-Vault.repo << 'EOF'
[base]
name=CentOS-\$releasever - Base - mirrors.aliyun.com
baseurl=https://mirrors.aliyun.com/centos-vault/7.9.2009/os/\$basearch/
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/centos-vault/RPM-GPG-KEY-CentOS-7

[updates]
name=CentOS-\$releasever - Updates - mirrors.aliyun.com
baseurl=https://mirrors.aliyun.com/centos-vault/7.9.2009/updates/\$basearch/
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/centos-vault/RPM-GPG-KEY-CentOS-7

[extras]
name=CentOS-\$releasever - Extras - mirrors.aliyun.com
baseurl=https://mirrors.aliyun.com/centos-vault/7.9.2009/extras/\$basearch/
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/centos-vault/RPM-GPG-KEY-CentOS-7
EOF

清华源

cat > CentOS-Vault.repo << 'EOF'
[base]
name=CentOS-\$releasever - Base - vault.centos.org
baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos-vault/7.9.2009/os/\$basearch/
gpgcheck=1
gpgkey=https://mirrors.tuna.tsinghua.edu.cn/centos-vault/RPM-GPG-KEY-CentOS-7

[updates]
name=CentOS-\$releasever - Updates - vault.centos.org
baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos-vault/7.9.2009/updates/\$basearch/
gpgcheck=1
gpgkey=https://mirrors.tuna.tsinghua.edu.cn/centos-vault/RPM-GPG-KEY-CentOS-7

[extras]
name=CentOS-\$releasever - Extras - vault.centos.org
baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos-vault/7.9.2009/extras/\$basearch/
gpgcheck=1
gpgkey=https://mirrors.tuna.tsinghua.edu.cn/centos-vault/RPM-GPG-KEY-CentOS-7
EOF

网易源

cat > CentOS-Vault.repo << 'EOF'
[base]
name=CentOS-\$releasever - Base - vault.163.com
baseurl=http://mirrors.163.com/centos-vault/7.9.2009/os/\$basearch/
gpgcheck=1
gpgkey=http://mirrors.163.com/centos-vault/RPM-GPG-KEY-CentOS-7

[updates]
name=CentOS-\$releasever - Updates - vault.163.com
baseurl=http://mirrors.163.com/centos-vault/7.9.2009/updates/\$basearch/
gpgcheck=1
gpgkey=http://mirrors.163.com/centos-vault/RPM-GPG-KEY-CentOS-7

[extras]
name=CentOS-\$releasever - Extras - vault.163.com
baseurl=http://mirrors.163.com/centos-vault/7.9.2009/extras/\$basearch/
gpgcheck=1
gpgkey=http://mirrors.163.com/centos-vault/RPM-GPG-KEY-CentOS-7
EOF

腾讯源

cat > CentOS-Vault.repo << 'EOF'
[base]
name=CentOS-\$releasever - Base - vault.tencent.com
baseurl=http://mirrors.cloud.tencent.com/centos-vault/7.9.2009/os/\$basearch/
gpgcheck=1
gpgkey=http://mirrors.cloud.tencent.com/centos-vault/RPM-GPG-KEY-CentOS-7

[updates]
name=CentOS-\$releasever - Updates - vault.tencent.com
baseurl=http://mirrors.cloud.tencent.com/centos-vault/7.9.2009/updates/\$basearch/
gpgcheck=1
gpgkey=http://mirrors.cloud.tencent.com/centos-vault/RPM-GPG-KEY-CentOS-7

[extras]
name=CentOS-\$releasever - Extras - vault.tencent.com
baseurl=http://mirrors.cloud.tencent.com/centos-vault/7.9.2009/extras/\$basearch/
gpgcheck=1
gpgkey=http://mirrors.cloud.tencent.com/centos-vault/RPM-GPG-KEY-CentOS-7
EOF

华为源

cat > CentOS-Vault.repo << 'EOF'
[base]
name=CentOS-\$releasever - Base - vault.huaweicloud.com
baseurl=https://repo.huaweicloud.com/centos-vault/7.9.2009/os/\$basearch/
gpgcheck=1
gpgkey=https://repo.huaweicloud.com/centos-vault/RPM-GPG-KEY-CentOS-7

[updates]
name=CentOS-\$releasever - Updates - vault.huaweicloud.com
baseurl=https://repo.huaweicloud.com/centos-vault/7.9.2009/updates/\$basearch/
gpgcheck=1
gpgkey=https://repo.huaweicloud.com/centos-vault/RPM-GPG-KEY-CentOS-7

[extras]
name=CentOS-\$releasever - Extras - vault.huaweicloud.com
baseurl=https://repo.huaweicloud.com/centos-vault/7.9.2009/extras/\$basearch/
gpgcheck=1
gpgkey=https://repo.huaweicloud.com/centos-vault/RPM-GPG-KEY-CentOS-7
EOF