我有一台阿里云香港服务器，想安装rz和sz命令，从服务器上面下载文档到本地，安装的时候报错：
# root @ localhost in /etc/yum.repos.d [11:31:28]
$ yum install lrzsz
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
http://mirrors.cloud.aliyuncs.com/centos/7/os/x86_64/repodata/repomd.xml: [Errno 14] curl#6 – "Could not resolve host: mirrors.cloud.aliyuncs.com; Unknown error"
Trying other mirror.
http://mirrors.cloud.aliyuncs.com/centos/7/extras/x86_64/repodata/repomd.xml: [Errno 14] curl#6 – "Could not resolve host: mirrors.cloud.aliyuncs.com; Unknown error"
Trying other mirror.
http://mirrors.cloud.aliyuncs.com/centos/7/updates/x86_64/repodata/repomd.xml: [Errno 14] curl#6 – "Could not resolve host: mirrors.cloud.aliyuncs.com; Unknown error"
Trying other mirror.
Resolving Dependencies
–> Running transaction check
—> Package lrzsz.x86_64 0:0.12.20-36.el7 will be installed
–> Finished Dependency Resolution
Dependencies Resolved
===================================================================================================================================================================
Package Arch Version Repository Size
===================================================================================================================================================================
Installing:
lrzsz x86_64 0.12.20-36.el7 base 78 k
Transaction Summary
===================================================================================================================================================================
Install 1 Package
Total download size: 78 k
Installed size: 181 k
Is this ok [y/d/N]: y
Downloading packages:
Delta RPMs disabled because /usr/bin/applydeltarpm not installed.
lrzsz-0.12.20-36.el7.x86_64.rp FAILED
http://mirrors.cloud.aliyuncs.com/centos/7/os/x86_64/Packages/lrzsz-0.12.20-36.el7.x86_64.rpm: [Errno 14] curl#6 – "Could not resolve host: mirrors.cloud.aliyuncs.com; Unknown error"
Trying other mirror.
Error downloading packages:
lrzsz-0.12.20-36.el7.x86_64: [Errno 256] No more mirrors to try.
注意看错误“Could not resolve host: mirrors.cloud.aliyuncs.com”，无法解析主机名，从网上看到的结果是DNS配置的有问题，按照阿里云论坛里的说法，我把DNS配置修改成这个样子：
nameserver 8.8.8.8
nameserver 114.114.114.114
nameserver 223.5.5.5 # 这两个是阿里云公网DNS
nameserver 223.6.6.6
再次安装依然是同样的错误。
解决方法：
这是创建阿里云服务器之后/etc/yum.repos.d目录下默认的所有repo文件：
# root @localhost in /etc/yum.repos.d [11:33:13]
$ ll
total 40K
-rw-r–r– 1 root root 676 Jan 28 11:27 CentOS-Base.repo
-rw-r–r– 1 root root 1.3K Nov 23 21:16 CentOS-CR.repo
-rw-r–r– 1 root root 649 Nov 23 21:16 CentOS-Debuginfo.repo
-rw-r–r– 1 root root 314 Nov 23 21:16 CentOS-fasttrack.repo
-rw-r–r– 1 root root 630 Nov 23 21:16 CentOS-Media.repo
-rw-r–r– 1 root root 1.3K Nov 23 21:16 CentOS-Sources.repo
-rw-r–r– 1 root root 5.6K Nov 23 21:16 CentOS-Vault.repo
-rw-r–r– 1 root root 231 Jan 28 11:33 epel.repo
把/etc/yum.repos.d/目录下所有的repo文件移动到其他目录，例如/tmp/yum。然后下载Centos-7.repo。
$ mv *.repo /tmp/yum
$ wget http://mirrors.aliyun.com/repo/Centos-7.repo
$ yum clean all
$ yum makecache
再次执行yum install lrzsz命令成功。
对比新下载的Centos-7.repo和之前的repo文件我们会发现，Centos-7.repo文件中的域名有三个，gpgcheck也全部设置为1：
(其中一个举例)
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
不明白为什么创建出来的ECS实例搞了那么多无用的repo文件，不直接使用Centos-7.repo这一个文件。
原创文章，作者：优速盾-小U，如若转载，请注明出处：https://www.cdnb.net/bbs/archives/30762
