[root@web1 ~]# cd /etc/yum.repos.d/ 
[root@web1 yum.repos.d]# ls
CentOS-Base.repo  CentOS-Debuginfo.repo  CentOS-Media.repo    CentOS-Vault.repo
CentOS-CR.repo    CentOS-fasttrack.repo  CentOS-Sources.repo
[root@web1 yum.repos.d]# 

2、下载相应的原包地址

[root@web1 yum.repos.d]# wget http://mirrors.163.com/.help/CentOS7-Base-163.repo
--2019-05-21 22:36:41--  http://mirrors.163.com/.help/CentOS7-Base-163.repo
Resolving mirrors.163.com (mirrors.163.com)... 59.111.0.251
Connecting to mirrors.163.com (mirrors.163.com)|59.111.0.251|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 1572 (1.5K) [application/octet-stream]
Saving to: ‘CentOS7-Base-163.repo.1’

100%[===============================================================================================>] 1,572       --.-K/s   in 0.001s  

2019-05-21 22:36:41 (2.84 MB/s) - ‘CentOS7-Base-163.repo.1’ saved [1572/1572]

[root@web1 yum.repos.d]# 

3、列出所有可安装的包

[root@web1 yum.repos.d]# yum list

4、如果一个163和base的源不够用的情况下，可以安装一个扩展源epel 

yum install -y epel-release
yum list |grep epel 

二、yum下载rpm包

1、下载包不安装

[root@web1 yum.repos.d]# yum install -y 包名 --downloadonly --downloaddir=路径 

2、已经安装的包要重新安装

[root@web1 yum.repos.d]# yum reinstall -y 包名 --downloadonly --downloaddir=路径

****将需要的rpm包打包好以后再使用时便可直接调用了****

参考：https://blog.csdn.net/mojianbin/article/details/78533260