问题：
刚刚在本地安装了CentOS7虚拟机，使用yum安装vim软件时（最小化安装只有vi没有vim）出现下面的报错
原因 ：
CentOS7 已于2024-6-30停止维护，官方镜像源已不可用，可以更换为阿里云镜像源
解决：
mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.bak
vi /etc/yum.repos.d/CentOS-Base.repo # 添加以下内容base
name=CentOS-7-Base-vault.aliyun.com
baseurl=https://mirrors.aliyun.com/centos-vault/7.9.2009/os/$basearch/
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7
enabled=1
updates
name=CentOS-7-Updates-vault.aliyun.com
baseurl=https://mirrors.aliyun.com/centos-vault/7.9.2009/updates/$basearch/
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7
enabled=1
extras
name=CentOS-7-Extras-vault.aliyun.com
baseurl=https://mirrors.aliyun.com/centos-vault/7.9.2009/extras/$basearch/
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7
enabled=1
清除旧缓存
sudo yum clean all
重建元数据缓存
sudo yum makecache
验证仓库列表
sudo yum repolist