Centos7安装gcc编辑器报Could not retrieve mirrorlist http:....... Could not resolve host:.....错

错误详情：

在Linux系统终端中输入gcc安装命令：yum -y install gcc gcc-c++ kernel-devel报错
示例：

 	[[e-mail] fei]# yum -y install gcc gcc-c++ kernel-devel
	已加载插件：fastestmirror, langpacks
	Loading mirror speeds from cached hostfile
	Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=7&		    		arch=x86_64&		repo=os&infra=stock error was
	14: curl#6 - "Could not resolve host: mirrorlist.centos.org; 未知的错误"

	 One of the configured repositories failed (未知),
	and yum doesn't have enough cached data to continue. At this 		  point the only
	safe thing yum can do is fail. There are a few ways to work "fix" this:


 1. Contact the upstream for the repository and get them to fix the problem.

 2. Reconfigure the baseurl/etc. for the rep`在这里插入代码片`ository, to point to a working
    upstream. This is most often useful if you are using a newer
    distribution release than is supported by the repository (and the
    packages for the previous distribution release still work).

 3. Run the command with the repository temporarily disabled
        yum --disablerepo=<repoid> ...

 4. Disable the repository permanently, so yum won't use it by default. Yum
    will then just ignore the repository until you permanently enable it
    again or use --enablerepo for temporary usage:

        yum-config-manager --disable <repoid>
    or
        subscription-manager repos --disable=<repoid>

 5. Configure the failing repository to be skipped, if it is unavailable.
    Note that yum will try to contact the repo. when it runs most commands,
    so will have to try and fail each time (and thus. yum will be be much
    slower). If it is a very temporary problem though, this is often a nice
    compromise:

        yum-config-manager --save --setopt=<repoid>.skip_if_unavailable=true
	Cannot find a valid baseurl for repo: base/7/x86_64

原因：

出现这种情况一般是因为你所在的Centos 7没有联网。

解决方法：

1.在终端输入命令 "nmcli d"查看网卡详情

示例：

[[e-mail] fei]# nmcli d
DEVICE      TYPE      STATE   CONNECTION 
virbr0      bridge    已连接  virbr0     
ens33       ethernet  已断开  --        
lo          loopback  未托管  --         
virbr0-nic  tun       未托管  --        

会看到第四行是"ens33 ethernet 已断开 – "

2.输入命令"cd /etc/sysconfig/network-scripts/"进入network-scripts

[[e-mail] 你的计算机名]# 会变成 [[e-mail] network-scripts]#

之后输入命令：“vim ifcfg-ens33”
示例：

[[e-mail] network-scripts]# vim ifcfg-ens33

进入以下界面
把最后一行的"ONBOOT=no"改成"ONBOOT=yes",保存退出
再依此输入一下命令：
“systemctl restart network”（重启网络）
“yum -y install gcc gcc-c++ kernel-devel”（安装gcc）

示例：

[[e-mail] network-scripts]# vim ifcfg-ens33
[[e-mail] network-scripts]# systemctl restart network
[[e-mail] network-scripts]# yum -y install gcc gcc-c++ kernel-		devel
已加载插件：fastestmirror, langpacks
Loading mirror speeds from cached hostfile
* base: mirrors.aliyun.com
* extras: mirrors.aliyun.com
* updates: mirrors.ustc.edu.cn
base                                                                          | 3.6 kB  	00:00:00     
extras                                                                        | 2.9 kB  	00:00:00     
updates                                                                       | 2.9 	kB  00:00:00     
(1/4): base/7/x86_64/group_gz                                                 	| 153 kB  	00:00:00     
(2/4): extras/7/x86_64/primary_db                                             | 194 kB  	00:00:00     
(3/4): base/7/x86_64/primary_db                                               | 6.1 MB  00:00:06     
(4/4): updates/7/x86_64/primary_db                                            | 2.1 MB  00:00:07     
正在解决依赖关系
--> 正在检查事务
---> 软件包 gcc.x86_64.0.4.8.5-39.el7 将被 安装
（内容太多，省略）

安装完成