apt-get

在使用apt-get update的時候，出現如下錯誤時：
E: Some index files failed to download, they have been ignored, or old ones used instead.
可以將目錄下/var/lib/apt/lists/partial/所有的檔案清掉，再次執行apt-get update即可！

自帶源在大陸不好，導致無法下載成功

Err http://security.ubuntu.com precise-security Release.gpg  
  Temporary failure resolving 'security.ubuntu.com'  
Err http://cn.archive.ubuntu.com precise InRelease  
.......

步驟

1. 首先可以對原檔案進行備份
   sudo cp /etc/apt/source.list /etc/apt/source.list.bak

2. 編輯源列表檔案（以管理員身份執行）
   sudo vim /etc/apt/source.list

3. 將檔案內容刪除，替換如下內容

   deb http://mirrors.aliyun.com/ubuntu/ vivid main restricted universe multiverse
   deb http://mirrors.aliyun.com/ubuntu/ vivid-security main restricted universe multiverse
   deb http://mirrors.aliyun.com/ubuntu/ vivid-updates main restricted universe multiverse
   deb http://mirrors.aliyun.com/ubuntu/ vivid-proposed main restricted universe multiverse
   deb http://mirrors.aliyun.com/ubuntu/ vivid-backports main restricted universe multiverse
   deb-src http://mirrors.aliyun.com/ubuntu/ vivid main restricted universe multiverse
   deb-src http://mirrors.aliyun.com/ubuntu/ vivid-security main restricted universe multiverse
   deb-src http://mirrors.aliyun.com/ubuntu/ vivid-updates main restricted universe multiverse
   deb-src http://mirrors.aliyun.com/ubuntu/ vivid-proposed main restricted universe multiverse

4、執行sudo apt-get update

5、執行sudo apt-get upgrade

yum

1、備份

mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup

2、下載新的CentOS-Base.repo 到/etc/yum.repos.d/
CentOS 5

wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-5.repo

CentOS 6

wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-6.repo

CentOS 7

wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo

3、之後執行yum makecache生成快取