sudo yum install filename 時提示没有可用软件包

安裝epel-release，epel-release也是一個源，需要安裝和電腦系統相對應的版本，也可以在Centos自帶“軟件”中搜索epel-release源，會自動搜索出需要的 epel-release源，安裝即可

eg：未安装源前---

[yu@localhost ~]$ sudo yum install axel

已加载插件：fastestmirror, langpacks

Repository base is listed more than once in the configuration

Repository updates is listed more than once in the configuration

Repository extras is listed more than once in the configuration

Repository centosplus is listed more than once in the configuration

Loading mirror speeds from cached hostfile

* base: mirrors.pubyun.com

* extras: mirrors.163.com

* updates: mirrors.163.com

没有可用软件包 axel。

错误：无须任何处理

安裝完源後：

[yu@localhost ~]$ sudo yum install axel

已加载插件：fastestmirror, langpacks

Repository base is listed more than once in the configuration

Repository updates is listed more than once in the configuration

Repository extras is listed more than once in the configuration

Repository centosplus is listed more than once in the configuration

Loading mirror speeds from cached hostfile

* base: mirrors.pubyun.com

* epel: mirrors.yun-idc.com

* extras: mirrors.163.com

* updates: mirrors.aliyun.com

正在解决依赖关系

--> 正在检查事务

---> 软件包 axel.x86_64.0.2.4-9.el7 将被 安装

--> 解决依赖关系完成

依赖关系解决

================================================================================

Package         架构              版本                   源               大小

================================================================================

正在安装:

axel            x86_64            2.4-9.el7              epel             54 k

事务概要

================================================================================

安装  1 软件包

总下载量：54 k

安装大小：112 k

Is this ok [y/d/N]: y

Downloading packages:

警告：/var/cache/yum/x86_64/7/epel/packages/axel-2.4-9.el7.x86_64.rpm: 头V3 RSA/SHA256 Signature, 密钥 ID 352c64e5: NOKEY

axel-2.4-9.el7.x86_64.rpm 的公钥尚未安装

axel-2.4-9.el7.x86_64.rpm                                  |  54 kB   00:00    

从 file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7 检索密钥

导入 GPG key 0x352C64E5:

用户ID     : "Fedora EPEL (7) <epel@fedoraproject.org>"

指纹       : 91e9 7d7c 4a5e 96f1 7f3e 888f 6a2f aea2 352c 64e5

软件包     : epel-release-7-5.noarch (@extras)

来自       : /etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7

是否继续？[y/N]：y

Running transaction check

Running transaction test

Transaction test succeeded

Running transaction

 正在安装    : axel-2.4-9.el7.x86_64                                       1/1

 验证中      : axel-2.4-9.el7.x86_64                                       1/1

已安装:

 axel.x86_64 0:2.4-9.el7                                                      

完毕！

运行以下命令生成缓存

   yum clean all    

   yum makecache

   yum update