Linux拥有众多的发行版，每个发行版都有提供镜像，但是，有些镜像的下载速度参差不齐，偶尔会有更新失败的情况。

下面以修改 CentOS 软件源为 未来云为例进行说明(镜像地址/香港节点镜像地址)：

1、备份原配置文件

# cp /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup 

2、下载新的CentOS-Base.repo 到/etc/yum.repos.d/

CentOS 5

# curl -o /etc/yum.repos.d/CentOS-Base.repo http://mirrors.niaoyun.com/repo/CentOS5-Base.repo

CentOS 6

# curl -o /etc/yum.repos.d/CentOS-Base.repo http://mirrors.niaoyun.com/repo/CentOS6-Base.repo

CentOS 7

# curl -o /etc/yum.repos.d/CentOS-Base.repo http://mirrors.niaoyun.com/repo/CentOS7-Base.repo

如果是香港节点：

CentOS 5

# curl -o /etc/yum.repos.d/CentOS-Base.repo http://hk.mirrors.niaoyun.com/repo/CentOS5-Base.repo

CentOS 6

# curl -o /etc/yum.repos.d/CentOS-Base.repo http://hk.mirrors.niaoyun.com/repo/CentOS6-Base.repo

CentOS 7

# curl -o /etc/yum.repos.d/CentOS-Base.repo http://hk.mirrors.niaoyun.com/repo/CentOS7-Base.repo

3、生成缓存

# yum makecache