在CentOS7执行安装命令时，比如yum update等，会出现下面的报错。
-
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，修改下面黄色标识的部分（只需要注释掉第一行，取消注释第二行就可以了）
# 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
完成上面两步，再重新执行yum update等其它安装命令就可以正常运行了。