Centos yum異常問題

搭建環境時碰到yum更新出問題了，報如下錯誤：

YumRepo Error: All mirror URLs are not using ftp, http[s] or file.

 Eg. $releasever is not a valid release or hasnt been released yet/

removing mirrorlist with no valid mirrors: /var/cache/yum/base/mirrorlist.txt

Error: Cannot retrieve repository metadata (repomd.xml) for repository: base. Please verify its path and try again

分析一般有三種原因：

1.有可能是防火牆阻礙了出網http請求或是ftp請求，service iptables status

2.有可能是dns不對，無法正常解析，換成8.8.8.8

3.系統取不到Release号

測試環境時使用ping www.baidu.com 顯示可以ping通，說明DNS沒有問題，那可能就是第三中原因了

需要修改*.repo源檔案中将$releasever變量全替換成6即可正常yum了

vim  /etc/yum.repos.d/CentOS6-Base-163.repo

【

[base]

name=CentOS-6 - Base - 163.com

baseurl=http://mirrors.163.com/centos/6/os/$basearch/

#mirrorlist=http://mirrorlist.centos.org/?release=6&arch=$basearch&repo=os

gpgcheck=1

gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-6

#released updates

[updates]

name=CentOS-6 - Updates - 163.com

baseurl=http://mirrors.163.com/centos/6/updates/$basearch/

#mirrorlist=http://mirrorlist.centos.org/?release=6&arch=$basearch&repo=updates

#additional packages that may be useful

[extras]

name=CentOS-6 - Extras - 163.com

baseurl=http://mirrors.163.com/centos/6/extras/$basearch/

#mirrorlist=http://mirrorlist.centos.org/?release=6&arch=$basearch&repo=extras

#additional packages that extend functionality of existing packages

[centosplus]

name=CentOS-6 - Plus - 163.com

baseurl=http://mirrors.163.com/centos/6/centosplus/$basearch/

#mirrorlist=http://mirrorlist.centos.org/?release=6&arch=$basearch&repo=centosplus

enabled=0