1. 问题描述

成功使用下面命令安装scl源后

[root@iZwz946ibli8ikuyqgtc58Z ~]# yum install centos-release-scl-rh

尝试使用scl安装redis5，报了下面错误：

[root@iZwz946ibli8ikuyqgtc58Z ~]# yum install rh-redis5-redis
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
Could not retrieve mirrorlist http://mirrorlist.centos.org?arch=x86_64&release=7&repo=sclo-rh error was
14: curl#6 - "Could not resolve host: mirrorlist.centos.org; Unknown error"One of the configured repositories failed (Unknown),and yum doesn't have enough cached data to continue. At this point the onlysafe 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 workingupstream. This is most often useful if you are using a newerdistribution release than is supported by the repository (and thepackages for the previous distribution release still work).3. Run the command with the repository temporarily disabledyum --disablerepo=<repoid> ...4. Disable the repository permanently, so yum won't use it by default. Yumwill then just ignore the repository until you permanently enable itagain or use --enablerepo for temporary usage:yum-config-manager --disable <repoid>orsubscription-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 muchslower). If it is a very temporary problem though, this is often a nicecompromise:yum-config-manager --save --setopt=<repoid>.skip_if_unavailable=trueCannot find a valid baseurl for repo: centos-sclo-rh/x86_64

上述错误信息表明无法检索镜像列表，原因是 http://mirrorlist.centos.org 已经停止服务了，因此我们需要更改scl源的baseUrl。

2. 解决方案

1. 使用cd命令到下面路径：

cd /etc/yum.repos.d

2. 查看是否有CentOS-SCLo-scl-rh.repo这个文件：

[root@iZwz946ibli8ikuyqgtc58Z yum.repos.d]# ls
CentOS-Base.repo  CentOS-SCLo-scl-rh.repo  epel.repo

3. 有的话使用vim编辑该文件：

vim CentOS-SCLo-scl-rh.repo

4. 将[centos-sclo-rh]下的内容改为下面内容：

[centos-sclo-rh]
name=CentOS-7 - SCLo rh
baseurl=http://vault.centos.org/centos/7/sclo/$basearch/rh/
gpgcheck=1
enabled=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-SIG-SCLo

更改完上述配置文件，便可以成功使用yum安装软件了：

[root@iZwz946ibli8ikuyqgtc58Z yum.repos.d]# yum install rh-redis5-redis
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
base                                                                                                                 | 3.6 kB  00:00:00
centos-sclo-rh                                                                                                       | 3.0 kB  00:00:00
epel                                                                                                                 | 4.3 kB  00:00:00
extras                                                                                                               | 2.9 kB  00:00:00
updates                                                                                                              | 2.9 kB  00:00:00
centos-sclo-rh/x86_64/primary_db                                                                                     | 3.4 MB  00:00:02
Resolving Dependencies