CentOS7 执行yum 命令出错_and yum doesn't have enough cached data to continu

在CentOS7执行安装命令时，比如yum update等，会出现下面的报错。
(下面只记录了一种方法，如果下面的方法不能解决，请尝试其他的方法)

Loaded plugins: fastestmirror
Error: invalid clean argument: 'yum'
 Mini usage:
 
 
clean [headers|packages|metadata|dbcache|plugins|expire-cache|all]
 
 
Remove cached data
[root@localhost ~]# yum install gcc -y
Loaded plugins: fastestmirror
Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=7&arch=x86_64&repo=os&infra=stock error was
14: curl#56 - "Recv failure: Connection reset by peer"
 
 
 
 
 One of the configured repositories failed (Unknown),
 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 repository, 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. Disable the repository, 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>
 
 
     4. 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

去修改它大致需要两步

第一步：vi /etc/resolv.conf，添加下面一行就可以了

nameserver 114.114.114.114（这是国内的dns服务器系统，还是比较好用的。谷歌的可以使用8.8.8.8）

修改完后service network restart进行重启，试一下yum update命令，应该就可以了。如果还不可以，可以再进行下一步。

第二步：进入 /etc/yum.repos.d ，编辑vi CentOS-Base.repo，找到如下的黑色加粗部分，注释掉第一行(mirrorlist)，取消注释第二行(baseurl)就可以了

# CentOS-Base.repo

#
# The mirror system uses the connecting IP address of the client and the
# update status of each mirror to pick mirrors that are updated to and
# geographically close to the client.  You should use this for CentOS updates
# unless you are manually picking other mirrors.
#
# If the mirrorlist= does not work for you, as a fall back you can try the
# remarked out baseurl= line instead.
#
#


[base]
name=CentOS-$releasever - Base
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os&infra=$infra
baseurl=http://mirror.centos.org/centos/$releasever/os/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7


#released updates
[updates]
name=CentOS-$releasever - Updates
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates&infra=$infra
baseurl=http://mirror.centos.org/centos/$releasever/updates/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7


#additional packages that may be useful
[extras]
name=CentOS-$releasever - Extras
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras&infra=$infra
baseurl=http://mirror.centos.org/centos/$releasever/extras/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7


#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-$releasever - Plus
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus&infra=$infra
baseurl=http://mirror.centos.org/centos/$releasever/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7


~                                                                                                                                                                      

"CentOS-Base.repo" 44L, 1664C

完成上面两步，再重新执行yum update等其它安装命令就可以正常运行了。