**我一般更新或安装软件使用的都是root权限，自己的测试虚拟机无所谓，如果你使用服务器请慎用root权限。**
命令行下输入
sudo apt-get update 报了一堆错误： Err http://cn.archive.ubuntu.com trusty InRelease Err http://cn.archive.ubuntu.com trusty-updates InRelease Err http://cn.archive.ubuntu.com trusty-backports InRelease Err http://cn.archive.ubuntu.com trusty Release.gpg W: Failed to fetch http://cn.archive.ubuntu.com/ubuntu/dists/trusty/InRelease根据提示的错误显示，可能是资源有问题，应该是访问被阻止，没有梯子。
推荐几个方案：
方案一：修改Ubuntu中/etc/hosts文件，添加可翻墙hosts（资源可以google或百度一下，这就不介绍了）
方案二：修改/etc/apt/source.list文件。将源改成163的或者阿里的：备份系统中的源列表，打开终端，输入：
sudo cp /etc/apt/sources.list /etc/apt/sources.list_backup 在/etc/apt/source.list文件中添加，下面内容，但别着急先看后面 deb http://mirrors.163.com/ubuntu/ vivid main restricted universe multiverse deb http://mirrors.163.com/ubuntu/ vivid-security main restricted universe multiverse deb http://mirrors.163.com/ubuntu/ vivid-updates main restricted universe multiverse deb http://mirrors.163.com/ubuntu/ vivid-proposed main restricted universe multiverse deb http://mirrors.163.com/ubuntu/ vivid-backports main restricted universe multiverse deb-src http://mirrors.163.com/ubuntu/ vivid main restricted universe multiverse deb-src http://mirrors.163.com/ubuntu/ vivid-security main restricted universe multiverse deb-src http://mirrors.163.com/ubuntu/ vivid-updates main restricted universe multiverse deb-src http://mirrors.163.com/ubuntu/ vivid-proposed main restricted universe multiverse deb-src http://mirrors.163.com/ubuntu/ vivid-backports main restricted universe multiverse 可是这个source.list文件是只读权限，无法进行修改。（1.桌面版sudo gedit /etc/apt/source.list修改，但是gedit 指令没有装，使用sudo apt-get install gedit又安装不了。
2.服务器版vim /etc/apt/source.list修改，又没有权限）
方案三：修改DNS（可行）
首先查看/etc/resolv.conf
cat /etc/resolv.conf
随后命令行执行：
sudo vi /etc/resolvconf/resolv.conf.d/base在里面插入（如果使用终端，可以直接复制粘贴）：
nameserver 8.8.8.8 nameserver 8.8.4.4 修改好，【!wq】退出保存， 然后执行： sudo resolvconf -u 执行结束后，查看/etc/resolv.conf文件，最下面就多了2行： cat /etc/resolv.conf 结果显示： #这块显示原来的信息 nameserver 8.8.8.8 nameserver 8.8.4.4 此时执行： sudo apt-get update可以运行，然后可以使用sudo apt-get install **指令了。
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问题又来了：下载仓库信息失败
实际上，有两种类型的下载仓库信息失败错误。如果你的错误是这样的：
W:Failed to fetch bzip2:/var/lib/apt/lists/partial/in.archive.ubuntu.comubuntudistsoneiricrestrictedbinary-i386Packages Hash Sum mismatch, W:Failed to fetch bzip2:/var/lib/apt/lists/partial/in.archive.ubuntu.comubuntudistsoneiricmultiversebinary-i386Packages Hash Sum mismatch, E:Some index files failed to download. They have been ignored, or old ones used instead 那么，你可以用以下命令修复： sudo rm -rf /var/lib/apt/lists/* sudo apt-get update=====================================================================
问题又来了：部分更新错误 在终端中运行更新会出现部分更新错误：
Not all updates can be installed Run a partial upgrade, to install as many updates as possible 在终端中运行以下命令来修复该错误： sudo apt-get install -f=====================================================================
同方案三：
当运行apt-get update后出现如下错误时： 出现了某些故障（-5 - 没有与主机名关联的地址）
E: Some index files failed to download, they have been ignored, or old ones used instead. 可以将目录下/var/lib/apt/lists/partial/所有的文件清掉（感觉不靠谱），再次运行apt-get update即可！如果还有问题，请检查resolvconf服务的配置文件:
/etc/resolvconf/resolv.conf.d/base
很可能是DNS的问题，可以使用公共的dns地址（操作参考方案三）： nameserver 8.8.8.8 nameserver 4.2.2.2 Ubuntu12.04自带源在大陆不好。可以更换其他源： 如果是其它ubuntu版本，只需把precise改为相应的版本的名字。hardy(8.04),lucid(10.04),maverick(10.10),oneiric(11.10),quantal(12.10),precise(12.04) trusty(14.04)
在/etc/apt/sources.list添加的内容有以下几种： 163
deb http://mirrors.163.com/ubuntu/ precise main restricted universe multiverse deb http://mirrors.163.com/ubuntu/ precise-security main restricted universe multiverse deb http://mirrors.163.com/ubuntu/ precise-updates main restricted universe multiverse deb http://mirrors.163.com/ubuntu/ precise-proposed main restricted universe multiverse deb http://mirrors.163.com/ubuntu/ precise-backports main restricted universe multiverse deb-src http://mirrors.163.com/ubuntu/ precise main restricted universe multiverse deb-src http://mirrors.163.com/ubuntu/ precise-security main restricted universe multiverse deb-src http://mirrors.163.com/ubuntu/ precise-updates main restricted universe multiverse deb-src http://mirrors.163.com/ubuntu/ precise-proposed main restricted universe multiverse deb-src http://mirrors.163.com/ubuntu/precise-backports main restricted universe multiverse sohu deb http://mirrors.sohu.com/ubuntu/ precise main restricted universe multiverse deb http://mirrors.sohu.com/ubuntu/ precise-security main restricted universe multiverse deb http://mirrors.sohu.com/ubuntu/ precise-updates main restricted universe multiverse deb http://mirrors.sohu.com/ubuntu/ precise-proposed main restricted universe multiverse deb http://mirrors.sohu.com/ubuntu/ precise-backports main restricted universe multiverse deb-src http://mirrors.sohu.com/ubuntu/ precise main restricted universe multiverse deb-src http://mirrors.sohu.com/ubuntu/ precisec-security main restricted universe multiverse deb-src http://mirrors.sohu.com/ubuntu/ precise-updates main restricted universe multiverse deb-src http://mirrors.sohu.com/ubuntu/ precise-proposed main restricted universe multiverse deb-src http://mirrors.sohu.com/ubuntu/ precise-backports main restricted universe multiverse ustc deb http://mirrors.ustc.edu.cn/ubuntu/ precise main restricted universe multiverse deb http://mirrors.ustc.edu.cn/ubuntu/ precise-security main restricted universe multiverse deb http://mirrors.ustc.edu.cn/ubuntu/ precise-updates main restricted universe multiverse deb http://mirrors.ustc.edu.cn/ubuntu/ precise-proposed main restricted universe multiverse deb http://mirrors.ustc.edu.cn/ubuntu/ precise-backports main restricted universe multiverse deb-src http://mirrors.ustc.edu.cn/ubuntu/ precise main restricted universe multiverse deb-src http://mirrors.ustc.edu.cn/ubuntu/ precise-security main restricted universe multiverse deb-src http://mirrors.ustc.edu.cn/ubuntu/ precise-updates main restricted universe multiverse deb-src http://mirrors.ustc.edu.cn/ubuntu/ precise-proposed main restricted universe multiverse deb-src http://mirrors.ustc.edu.cn/ubuntu/ precise-backports main restricted universe multiverse 备注：文中方案一、三，尝试过可行，解决方案来自网络。
