备份自带源

[root@localhost ~]# cd /etc/yum.repos.d/
[root@localhost yum.repos.d]# ls
CentOS-Base.repo  CentOS-CR.repo  CentOS-Debuginfo.repo  CentOS-fasttrack.repo  CentOS-Media.repo  CentOS-Sources.repo  CentOS-Vault.repo  CentOS-x86_64-kernel.repo
[root@localhost yum.repos.d]# cp CentOS-Base.repo CentOS-Base.repo.bak
[root@localhost yum.repos.d]# 

清华大学开源镜像源（参考https://mirrors.tuna.tsinghua.edu.cn/help/centos/）

编辑 /etc/yum.repos.d/ 中的相应文件，在 mirrorlist= 开头行前面加 # 注释掉；并将 baseurl= 开头行撤销注释（如果被注释的话）。 对于 CentOS 7 ，请把该行内的域名（例如mirror.centos.org）替换为
mirrors.tuna.tsinghua.edu.cn。 对于 CentOS 8 ，请把 mirror.centos.org/$contentdir 替换为
mirrors.tuna.tsinghua.edu.cn/centos。

以上步骤可以被下方的命令一步完成，

# 对于 CentOS 7
sudo sed -e 's|^mirrorlist=|#mirrorlist=|g' 
         -e 's|^#baseurl=http://mirror.centos.org|baseurl=https://mirrors.tuna.tsinghua.edu.cn|g' 
         -i.bak 
         /etc/yum.repos.d/CentOS-*.repo

# 对于 CentOS 8
sudo sed -e 's|^mirrorlist=|#mirrorlist=|g' 
         -e 's|^#baseurl=http://mirror.centos.org/$contentdir|baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos|g' 
         -i.bak 
         /etc/yum.repos.d/CentOS-*.repo

注意其中的*通配符，如果只需要替换一些文件中的源，请自行增删。

注意，如果需要启用其中一些 repo，需要将其中的 enabled=0 改为 enabled=1。

最后，更新软件包缓存

sudo yum makecache

阿里源

我在这里直接提供一个模板

全复制替换即可

方式1：

gedit命令

[ooyy1102@localhost yum.repos.d]$ sudo gedit CentOS-Base.repo 

我们信任您已经从系统管理员那里了解了日常注意事项。
总结起来无外乎这三点：

    #1) 尊重别人的隐私。
    #2) 输入前要先思考(后果和风险)。
    #3) 权力越大，责任越大。

[sudo] ooyy1102 的密码：

在这个界面直接编辑即可。

方式2：

vim命令

i 开始插入，更改完成后esc :wq!保存！

[root@localhost ~]# vim /etc/yum.repos.d/CentOS-Base.repo

# CentOS-Base.repo

#

# The mirror system uses the connecting IP address of the client and the

# update status of each mirror to pick mirrors that are updated to and

# geographically close to the client.  You should use this for CentOS updates

# unless you are manually picking other mirrors.

#

# If the mirrorlist= does not work for you, as a fall back you can try the 

# remarked out baseurl= line instead.

#
#

[base]
name=CentOS-$releasever - Base - mirrors.aliyun.com
failovermethod=priority
baseurl=http://mirrors.aliyun.com/centos/$releasever/os/$basearch/
        http://mirrors.aliyuncs.com/centos/$releasever/os/$basearch/
        http://mirrors.cloud.aliyuncs.com/centos/$releasever/os/$basearch/
gpgcheck=1
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7

#released updates 
[updates]
name=CentOS-$releasever - Updates - mirrors.aliyun.com
failovermethod=priority
baseurl=http://mirrors.aliyun.com/centos/$releasever/updates/$basearch/
        http://mirrors.aliyuncs.com/centos/$releasever/updates/$basearch/
        http://mirrors.cloud.aliyuncs.com/centos/$releasever/updates/$basearch/
gpgcheck=1
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7

#additional packages that may be useful
[extras]
name=CentOS-$releasever - Extras - mirrors.aliyun.com
failovermethod=priority
baseurl=http://mirrors.aliyun.com/centos/$releasever/extras/$basearch/
        http://mirrors.aliyuncs.com/centos/$releasever/extras/$basearch/
        http://mirrors.cloud.aliyuncs.com/centos/$releasever/extras/$basearch/
gpgcheck=1
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7

#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-$releasever - Plus - mirrors.aliyun.com
failovermethod=priority
baseurl=http://mirrors.aliyun.com/centos/$releasever/centosplus/$basearch/
        http://mirrors.aliyuncs.com/centos/$releasever/centosplus/$basearch/
        http://mirrors.cloud.aliyuncs.com/centos/$releasever/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7

#contrib - packages by Centos Users
[contrib]
name=CentOS-$releasever - Contrib - mirrors.aliyun.com
failovermethod=priority
baseurl=http://mirrors.aliyun.com/centos/$releasever/contrib/$basearch/
        http://mirrors.aliyuncs.com/centos/$releasever/contrib/$basearch/
        http://mirrors.cloud.aliyuncs.com/centos/$releasever/contrib/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7

更改完成后

sudo yum makecache

完成这样就可以安装需要的软件了！！