redhat系统中，如果你想要更新yum仓库，它会提示让你注册才能更新，因为centos和redhat基本相同，所以我把yum这一套全换成centos的。

1. 删除已安装的yum包

cd /etc/rpm/rm -rf ./m*

2. 下载centos的yum包

22  wget https://mirrors.aliyun.com/centos/7/os/x86_64/Packages/yum-metadata-parser-1.1.4-10.el7.x86_64.rpm   24  wget https://mirrors.aliyun.com/centos/7/os/x86_64/Packages/yum-utils-1.1.31-40.el7.noarch.rpm   25  wget https://mirrors.aliyun.com/centos/7/os/x86_64/Packages/yum-3.4.3-158.el7.centos.noarch.rpm   26  wget https://mirrors.aliyun.com/centos/7/os/x86_64/Packages/yum-plugin-fastestmirror-1.1.31-45.el7.noarch.rpm   28  wget https://mirrors.aliyun.com/centos/7/os/x86_64/Packages/python-urlgrabber-3.10-8.el7.noarch.rpm

如果出现404错误，请去搜索关键词查询最新rpm包的链接。

3. 强制安装rpm包

--force --nodeps为忽略依赖检测的强制安装

rpm -ivh python-urlgrabber-3.10-8.el7.noarch.rpm --force --nodepsrpm -ivh yum* --force --nodeps

4. 查看yum包是否安装好

[root@localhost yum.repos.d]# rpm -qa |grep yumyum-metadata-parser-1.1.4-10.el7.x86_64yum-utils-1.1.31-45.el7.noarchyum-3.4.3-158.el7.centos.noarchyum-plugin-fastestmirror-1.1.31-45.el7.noarch

5. 修改repo

下载源文件

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

需要把Centos-7.repo文件中的$releasever全部替换为7

67  cd /etc/yum.repos.d/   68  ls   69  vim CentOS-Base.repo

在vim中执行:%s/$releasever/7/g快速替换。保存退出。

6. 清空重载yum

yum clean allyum update# 最后查看一下yum列表yum list