最近在ubuntu11.10下安装支持多媒体播放的插件时遇到一些问题，在此小记一下。
首先是ubuntu11.10的安装，基本上是一键安装，在此不细说。
1.此版本和以前使用的ubuntu版本风格不太一致，为此在使用时一度不太习惯。
1）软件源服务器的选择
在左侧列表中有一个System Settings,点击进入有3大选项，选择System里面的Software Sources，出现一个对话框，第一项为Ubuntu Software，此项里有一个DownLoad From选择中国服务器mirrors.163.com（网易）服务源，保存退出。
2）终端的使用
终端的使用不在像以前的版本一样，直接右键桌面就可以出现。Ubuntu11.10使用快捷键Ctrl+Atrl+T，然后可以将终端锁定在左侧的菜单栏里，方便使用。
2.安装插件
使用命令
sudo apt-get install ubuntu-restricted-extras
时出现错误：
E: Unable to locate package ubuntu-restricted-extras
即找不到安装的包，在网上找资料，得到的答案是
sudo apt-get update
sudo apt-get upgrade
在使用sudo apt-get update命令时遇到问题
E: Unable to lock directory /var/lib/apt/lists/
查资料得到方法：
sudo rm /var/lib/apt/lists/lock
测试通过！
在sudo apt-get update的过程中遇到问题：
.Ign http://extras.ubuntu.com natty/main TranslationIndex
.Err http://extras.ubuntu.com natty/main Sources
. Not Found
.Err http://extras.ubuntu.com natty/main i386 Packages
. Not Found
.Ign http://extras.ubuntu.com natty/main Translation-en_US
.Err http://security.ubuntu.com natty-security/universe Sources
. Not Found [IP: 91.189.92.200 ]
.Err http://security.ubuntu.com natty-security/multiverse Sources
. Not Found [IP: 91.189.92.200 ]
.Ign http://extras.ubuntu.com natty/main Translation-en
.Err http://security.ubuntu.com natty-security/universe i386 Packages
. Not Found [IP: 91.189.92.200 ]
.Err http://security.ubuntu.com natty-security/multiverse i386 Packages
. Not Found [IP: 91.189.92.200 ]
.Err http://security.ubuntu.com natty-security/main Sources
. Not Found [IP: 91.189.92.200 ]
.Err http://security.ubuntu.com natty-security/restricted Sources
. Not Found [IP: 91.189.92.200 ]
.Err http://security.ubuntu.com natty-security/main i386 Packages
. Not Found [IP: 91.189.92.200 ]
.Err http://security.ubuntu.com natty-security/restricted i386 Packages
. Not Found [IP: 91.189.92.200 ]
.Ign http://security.ubuntu.com natty-security/main Translation-en_US
.Ign http://security.ubuntu.com natty-security/main Translation-en
.Ign http://security.ubuntu.com natty-security/multiverse Translation-en_US
.Ign http://security.ubuntu.com natty-security/multiverse Translation-en
.Ign http://security.ubuntu.com natty-security/restricted Translation-en_US
.Ign http://security.ubuntu.com natty-security/restricted Translation-en
.Ign http://security.ubuntu.com natty-security/universe Translation-en_US
.Ign http://security.ubuntu.com natty-security/universe Translation-en
.W: Failed to fetch http://cn.archive.ubuntu.com/ubuntu/dists/natty/main/source/Sources 404 Not Found
.
.W: Failed to fetch http://cn.archive.ubuntu.com/ubuntu/dists/natty/restricted/source/Sources 404 Not Found
.
.W: Failed to fetch http://cn.archive.ubuntu.com/ubuntu/dists/natty/universe/source/Sources 404 Not Found
.
.W: Failed to fetch http://cn.archive.ubuntu.com/ubuntu/dists/natty/multiverse/source/Sources 404 Not Found
.
.W: Failed to fetch http://cn.archive.ubuntu.com/ubuntu/dists/natty/main/binary-i386/Packages 404 Not Found
.
.W: Failed to fetch http://cn.archive.ubuntu.com/ubuntu/dists/natty/restricted/binary-i386/Packages 404 Not Found
.
.W: Failed to fetch http://cn.archive.ubuntu.com/ubuntu/dists/natty/universe/binary-i386/Packages 404 Not Found
.
.W: Failed to fetch http://cn.archive.ubuntu.com/ubuntu/dists/natty/multiverse/binary-i386/Packages 404 Not Found
.
.W: Failed to fetch http://cn.archive.ubuntu.com/ubuntu/dists/natty-updates/main/source/Sources 404 Not Found
.
.W: Failed to fetch http://cn.archive.ubuntu.com/ubuntu/dists/natty-updates/restricted/source/Sources 404 Not Found
.
.W: Failed to fetch http://cn.archive.ubuntu.com/ubuntu/dists/natty-updates/universe/source/Sources 404 Not Found
.
.W: Failed to fetch http://cn.archive.ubuntu.com/ubuntu/dists/natty-updates/multiverse/source/Sources 404 Not Found
.
.W: Failed to fetch http://cn.archive.ubuntu.com/ubuntu/dists/natty-updates/main/binary-i386/Packages 404 Not Found
.
.W: Failed to fetch http://cn.archive.ubuntu.com/ubuntu/dists/natty-updates/restricted/binary-i386/Packages 404 Not Found
.
.W: Failed to fetch http://cn.archive.ubuntu.com/ubuntu/dists/natty-updates/universe/binary-i386/Packages 404 Not Found
.
.W: Failed to fetch http://cn.archive.ubuntu.com/ubuntu/dists/natty-updates/multiverse/binary-i386/Packages 404 Not Found
.
.W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/natty-security/universe/source/Sources 404 Not Found [IP: 91.189.92.200 80]
.
.W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/natty-security/multiverse/source/Sources 404 Not Found [IP: 91.189.92.200 80]
.
.W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/natty-security/universe/binary-i386/Packages 404 Not Found [IP: 91.189.92.200 80]
.
.W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/natty-security/multiverse/binary-i386/Packages 404 Not Found [IP: 91.189.92.200 80]
.
.W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/natty-security/main/source/Sources 404 Not Found [IP: 91.189.92.200 80]
.
.W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/natty-security/restricted/source/Sources 404 Not Found [IP: 91.189.92.200 80]
.
.W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/natty-security/main/binary-i386/Packages 404 Not Found [IP: 91.189.92.200 80]
.
.W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/natty-security/restricted/binary-i386/Packages 404 Not Found [IP: 91.189.92.200 80]
.
.W: Failed to fetch http://extras.ubuntu.com/ubuntu/dists/natty/main/source/Sources 404 Not Found
.
.W: Failed to fetch http://extras.ubuntu.com/ubuntu/dists/natty/main/binary-i386/Packages 404 Not Found
.
.E: Some index files failed to download. They have been ignored, or old ones used instead.
.chaihuasong@chaihuasong:~$ sudo apt-get install git
.Reading package lists... Done
.Building dependency tree
.Reading state information... Done
.E: Unable to locate package git
继续找资料，在chaihuasong的博客里名为ubuntu下sudo apt-get update Sources 404 Not Found [IP: 91.189.92.200 80]解决办法
里获得答案：
把以下内容复制、粘贴到etc/apt/sources.list文件里的最开始部分，保存并退出。
deb http://mirrors.163.com/ubuntu/ lucid main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ lucid-security main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ lucid-updates main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ lucid-proposed main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ lucid-backports main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ lucid main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ lucid-security main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ lucid-updates main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ lucid-proposed main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ lucid-backports main restricted universe multiverse
测试通过。（虽然在更新的过程中仍然有提示很多package失败和错误）
然后使用命令：
sudo apt-get update
sudo apt-get upgrade
sudo apt-get install ubuntu-restricted-extras
即支持多媒体播放的插件安装成功！