1、事件描述:CentOS7下使用tree命令,发现该命令没有被安装,在安装的过程中发现yum报错
| 1 2 3 4 5 | [root@openstack-01 ~]# tree -dbash: tree: 未找到命令...[root@openstack-01 ~]# yum -y install tree已加载插件:fastestmirror, langpacksRepodata is over 2 weeks old. Install yum-cron? Or run: yum makecache fast | 
2、处理过程
a、直接执行yum makecache fast
[root@openstack-01 ~]# yum makecache fast
已加载插件:fastestmirror, langpacks
Repodata is over 2 weeks old. Install yum-cron? Or run: yum makecache fast
备注:根据它的提示信息执行操作,发现提示信息依旧
b、清除yum缓存
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 | [root@openstack-01 ~]# yum clean all已加载插件:fastestmirror, langpacksRepodata is over 2 weeks old. Install yum-cron? Or run: yum makecache fast正在清理软件源: base centos-ceph-hammer centos-openstack-mitaka centos-qemu-ev extras updatesCleaning up everythingCleaning up list of fastest mirrors[5]-  已杀死               yum update[root@openstack-01 ~]# yum makecache已加载插件:fastestmirror, langpacksCould not retrieve mirrorlist http://mirrorlist.centos.org/?release=7&arch=x86_64&repo=os&infra=stock error was14: 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 dois fail. There are a few ways to work "fix"this:     1. Contact the upstream forthe repository and get them to fix the problem.     2. Reconfigure the baseurl/etc. forthe repository, to point to a working        upstream. This is most often useful ifyou are using a newer        distribution release than is supported by the repository (and the        packages forthe previous distribution release still work).     3. Disable the repository, so yum won't use it by default. Yum will then        just ignore the repository untilyou permanently enableit again or use        --enablerepo fortemporary usage:            yum-config-manager --disable <repoid>     4. Configure the failing repository to be skipped, ifit 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=trueCannot finda valid baseurl forrepo: base/7/x86_64 | 
这时候我开始怀疑是不是我的yum所在的网络也存在问题
c、检测网络连通性状态,发现的确是网络存在问题
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 | 检查了网卡配置,发现DNS配置存在一些问题,手动修改并重置网卡信息,网络恢复正常[root@openstack-01 ~]# yum clean all已加载插件:fastestmirror, langpacks正在清理软件源: base centos-ceph-hammer centos-openstack-mitaka centos-qemu-ev extras updatesCleaning up everything[root@openstack-01 ~]# yum -y install tree已加载插件:fastestmirror, langpacksbase                                                                                                                         | 3.6 kB  00:00:00     centos-ceph-hammer                                                                                                           | 2.9 kB  00:00:00     centos-openstack-mitaka                                                                                                      | 2.9 kB  00:00:00     centos-qemu-ev                                                                                                               | 2.9 kB  00:00:00     extras                                                                                                                       | 3.4 kB  00:00:00     updates                                                                                                                      | 3.4 kB  00:00:00     (1/7): centos-ceph-hammer/7/x86_64/primary_db|  30 kB  00:00:01     (2/7): extras/7/x86_64/primary_db| 132 kB  00:00:00     (3/7): updates/7/x86_64/primary_db| 4.9 MB  00:00:01     (4/7): centos-openstack-mitaka/x86_64/primary_db| 452 kB  00:00:04     (5/7): base/7/x86_64/primary_db| 5.3 MB  00:00:07     (6/7): base/7/x86_64/group_gz| 155 kB  00:00:15     (7/7): centos-qemu-ev/7/x86_64/primary_db|  23 kB  00:00:16     Determining fastest mirrors * base: mirrors.zju.edu.cn * extras: mirrors.aliyun.com * updates: mirrors.aliyun.com正在解决依赖关系--> 正在检查事务---> 软件包 tree.x86_64.0.1.6.0-10.el7 将被 安装--> 解决依赖关系完成依赖关系解决==================================================================================================================================================== Package                         架构                              版本                                       源                               大小====================================================================================================================================================正在安装: tree                            x86_64                            1.6.0-10.el7                               base                             46 k事务概要====================================================================================================================================================安装  1 软件包总下载量:46 k安装大小:87 kDownloading packages:tree-1.6.0-10.el7.x86_64.rpm                                                                                                 |  46 kB  00:00:00     Running transaction checkRunning transaction testTransaction testsucceededRunning transaction  正在安装    : tree-1.6.0-10.el7.x86_64                                                                                                        1/1  验证中      : tree-1.6.0-10.el7.x86_64                                                                                                        1/1已安装:  tree.x86_64 0:1.6.0-10.el7                                                                                                                        完毕![root@openstack-01 ~]# tree.├── anaconda-ks.cfg├── keystonerc_admin├── keystonerc_demo├── packstack-answers-20160505-132946.txt├── packstack-answers-20160505-134047.txt├── packstack-answers-20160505-152256.txt├── \345\205\254\345\205\261├── \346\250\241\346\235\277├── \350\247\206\351\242\221├── \345\233\276\347\211\207├── \346\226\207\346\241\243├── \344\270\213\350\275\275├── \351\237\263\344\271\220└── \346\241\214\351\235\242    ├── \346\234\252\345\221\275\345\220\215\346\226\207\344\273\266\345\244\271    └── \346\234\252\345\221\275\345\220\215\346\226\207\344\273\266\345\244\271\ 210 directories, 6 files | 
 
                    
                     
                    
                 
                    
                 
         
