在CentOS7執行安裝命令時，比如yum update等，會出現下面的報錯。

Loaded plugins: fastestmirror
Error: invalid clean argument: 'yum'
 Mini usage:


clean [headers|packages|metadata|dbcache|plugins|expire-cache|all]


Remove cached data
[[email protected] ~]# 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
 

去修改它大致需要兩步

第一步：vi /etc/resolv.conf，新增下面一行就可以了

nameserver 114.114.114.114（這是國內的dns伺服器系統，還是比較好用的。谷歌的可以使用8.8.8.8）

修改完後service network restart進行重啟，試一下yum update命令，應該就可以了。如果還不可以，可以再進行下一步。

第二步：進入 /etc/yum.repos.d ，編輯vi CentOS-Base.repo，修改下面黃色標識的部分（只需要註釋掉第一行，取消註釋第二行就可以了）

# 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

完成上面兩步，再重新執行yum update等其它安裝命令就可以正常運行了。