问题：
[root@localhost yum.repos.d]# yum install wget
已加载插件：fastestmirror
Loading mirror speeds from cached hostfile
There are no enabled repos.
Run "yum repolist all" to see the repos you have.
To enable Red Hat Subscription Management repositories:
subscription-manager repos --enable <repo>
To enable custom repositories:
yum-config-manager --enable <repo>
[root@localhost yum.repos.d]# yum repolist all
已加载插件：fastestmirror
Loading mirror speeds from cached hostfile
源标识 源名称 状态
C7.0.1406-base/x86_64 CentOS-7.0.1406 - Base 禁用
C7.0.1406-centosplus/x86_64 CentOS-7.0.1406 - CentOSPlus 禁用
C7.0.1406-extras/x86_64 CentOS-7.0.1406 - Extras 禁用
C7.0.1406-fasttrack/x86_64 CentOS-7.0.1406 - CentOSPlus 禁用
C7.0.1406-updates/x86_64 CentOS-7.0.1406 - Updates 禁用
C7.1.1503-base/x86_64 CentOS-7.1.1503 - Base 禁用
C7.1.1503-centosplus/x86_64 CentOS-7.1.1503 - CentOSPlus 禁用
C7.1.1503-extras/x86_64 CentOS-7.1.1503 - Extras 禁用
C7.1.1503-fasttrack/x86_64 CentOS-7.1.1503 - CentOSPlus 禁用
C7.1.1503-updates/x86_64 CentOS-7.1.1503 - Updates 禁用
C7.2.1511-base/x86_64 CentOS-7.2.1511 - Base 禁用
C7.2.1511-centosplus/x86_64 CentOS-7.2.1511 - CentOSPlus 禁用
C7.2.1511-extras/x86_64 CentOS-7.2.1511 - Extras 禁用
C7.2.1511-fasttrack/x86_64 CentOS-7.2.1511 - CentOSPlus 禁用
C7.2.1511-updates/x86_64 CentOS-7.2.1511 - Updates 禁用
C7.3.1611-base/x86_64 CentOS-7.3.1611 - Base 禁用
C7.3.1611-centosplus/x86_64 CentOS-7.3.1611 - CentOSPlus 禁用
C7.3.1611-extras/x86_64 CentOS-7.3.1611 - Extras 禁用
C7.3.1611-fasttrack/x86_64 CentOS-7.3.1611 - CentOSPlus 禁用
C7.3.1611-updates/x86_64 CentOS-7.3.1611 - Updates 禁用
base-debuginfo/x86_64 CentOS-7 - Debuginfo 禁用
base-source/7 CentOS-7 - Base Sources 禁用
c7-media CentOS-7 - Media 禁用
centosplus-source/7 CentOS-7 - Plus Sources 禁用
cr/7/x86_64 CentOS-7 - cr 禁用
extras-source/7 CentOS-7 - Extras Sources 禁用
fasttrack/7/x86_64 CentOS-7 - fasttrack 禁用
updates-source/7 CentOS-7 - Updates Sources 禁用
repolist: 0
解决方法：
因为我的系统为：centos7 ：所以使用文件：CentOS7-Base-163.repo 下载该文件到
[root@localhost yum.repos.d]# yum clean all
已加载插件：fastestmirror
正在清理软件源： base extras updates
Cleaning up everything
Maybe you want: rm -rf /var/cache/yum, to also free up space taken by orphaned data from disabled or removed repos
Cleaning up list of fastest mirrors
[root@localhost yum.repos.d]# yum makecache
已加载插件：fastestmirror
base | 3.6 kB 00:00
extras | 3.4 kB 00:00
updates | 3.4 kB 00:00
(1/12): base/7/x86_64/group_gz | 166 kB 00:00
(2/12): base/7/x86_64/primary_db | 5.9 MB 00:00
(3/12): base/7/x86_64/filelists_db | 6.9 MB 00:00
(4/12): base/7/x86_64/other_db | 2.5 MB 00:00
(5/12): extras/7/x86_64/prestodelta | 100 kB 00:00
(6/12): extras/7/x86_64/filelists_db | 603 kB 00:00
(7/12): extras/7/x86_64/primary_db | 205 kB 00:00
(8/12): extras/7/x86_64/other_db | 126 kB 00:00
(9/12): updates/7/x86_64/prestodelta | 679 kB 00:00
(10/12): updates/7/x86_64/filelists_db | 3.4 MB 00:00
(11/12): updates/7/x86_64/other_db | 578 kB 00:00
(12/12): updates/7/x86_64/primary_db | 6.0 MB 00:00
Determining fastest mirrors
元数据缓存已建立
[root@localhost yum.repos.d]# yum repolist
已加载插件：fastestmirror
Loading mirror speeds from cached hostfile
源标识 源名称 状态
base/7/x86_64 CentOS-7 - Base - 163.com 9,911
extras/7/x86_64 CentOS-7 - Extras - 163.com 434
updates/7/x86_64 CentOS-7 - Updates - 163.com 1,614
repolist: 11,959
上面repolist 显示安装成功
测试： yum install wget 则安装成功
参考：https://blog.csdn.net/qq_39720249/article/details/84104646