不得不承认，到现在为止还有很多服务器在用旧的ubuntu版本，比如我在buyvm上的服务器，现在还是11.04的版本，在执行apt-get update的时候，不是IGN就是404。
这是因为，ubuntu已经不再维护这些源了，那么我们仍然在使用的怎么办？改一下吧：
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- deb http://old-releases.ubuntu.com/ubuntu/ natty main restricted universe multiverse
- deb http://old-releases.ubuntu.com/ubuntu/ natty-security main restricted universe multiverse
- deb http://old-releases.ubuntu.com/ubuntu/ natty-updates main restricted universe multiverse
- deb http://old-releases.ubuntu.com/ubuntu/ natty-proposed main restricted universe multiverse
- deb http://old-releases.ubuntu.com/ubuntu/ natty-backports main restricted universe multiverse
- deb-src http://old-releases.ubuntu.com/ubuntu/ natty main restricted universe multiverse
- deb-src http://old-releases.ubuntu.com/ubuntu/ natty-security main restricted universe multiverse
- deb-src http://old-releases.ubuntu.com/ubuntu/ natty-updates main restricted universe multiverse
- deb-src http://old-releases.ubuntu.com/ubuntu/ natty-proposed main restricted universe multiverse
- deb-src http://old-releases.ubuntu.com/ubuntu/ natty-backports main restricted universe multiverse
其实这挺让人痛苦的。。。ubuntu的更新又是这么频繁 。。
参考：http://askubuntu.com/questions/345000/updating-ubuntu-server-apt-get-gives-me-404-not-found