sudo apt-get update这是我在 Ubuntu 12.04 上运行后输出的结尾：
Ign http://apt.typesafe.com unicorn/main Translation-en
35% [Working]W: Failed to fetch http://ppa.launchpad.net/eclipse-team/ppa/ubuntu/dists/precise/main/source/Sources 404 Not Found
W: Failed to fetch http://ppa.launchpad.net/eclipse-team/ppa/ubuntu/dists/precise/main/binary-amd64/Packages 404 Not Found
W: Failed to fetch http://ppa.launchpad.net/eclipse-team/ppa/ubuntu/dists/precise/main/binary-i386/Packages 404 Not Found
E: Some index files failed to download. They have been ignored, or old ones used instead.
我的Ubuntu版本是12.04。
更新：
我用这个命令计算出日期
find /etc/apt -name '*.list' -exec bash -c 'echo -e "\n$1\n"; cat -n "$1"' _ '{}' \;
这是输出：
/etc/apt/sources.list
1 #############################################################
2 ################### OFFICIAL UBUNTU REPOS ###################
3 #############################################################
4
5 ###### Ubuntu Main Repos
6 deb http://mirror.mirohost.net/ubuntu/ precise main restricted universe multiverse
7 deb-src http://mirror.mirohost.net/ubuntu/ precise main restricted universe multiverse
8
9 ###### Ubuntu Update Repos
10 deb http://mirror.mirohost.net/ubuntu/ precise-security main restricted universe multiverse
11 deb http://mirror.mirohost.net/ubuntu/ precise-updates main restricted universe multiverse
12 deb http://mirror.mirohost.net/ubuntu/ precise-backports main restricted universe multiverse
13 deb-src http://mirror.mirohost.net/ubuntu/ precise-security main restricted universe multiverse
14 deb-src http://mirror.mirohost.net/ubuntu/ precise-updates main restricted universe multiverse
15 deb-src http://mirror.mirohost.net/ubuntu/ precise-backports main restricted universe multiverse
16
17 ###### Ubuntu Partner Repo
18 # deb http://archive.canonical.com/ubuntu precise partner
19 # deb-src http://archive.canonical.com/ubuntu precise partner
20
21 ###### Ubuntu Extras Repo
22 # deb http://extras.ubuntu.com/ubuntu precise main
23 # deb-src http://extras.ubuntu.com/ubuntu precise main
24 # deb http://linux.dropbox.com/ubuntu precise main
25 # deb-src http://linux.dropbox.com/ubuntu precise main
/etc/apt/source.list
1 deb http://security.ubuntu.com/ubuntu precise-security main universe
/etc/apt/sources.list.d/webupd8team-y-ppa-manager-precise.list
1 # deb http://ppa.launchpad.net/webupd8team/y-ppa-manager/ubuntu precise main
2 # deb-src http://ppa.launchpad.net/webupd8team/y-ppa-manager/ubuntu precise main
/etc/apt/sources.list.d/google-talkplugin.list
1 ### THIS FILE IS AUTOMATICALLY CONFIGURED ###
2 # You may comment out this entry, but any other modifications may be lost.
3 deb http://dl.google.com/linux/talkplugin/deb/ stable main
/etc/apt/sources.list.d/playonlinux.list
1 # deb http://deb.playonlinux.com/ quantal main
/etc/apt/sources.list.d/private-ppa.launchpad.net_commercial-ppa-uploaders_intellij-idea-ce_ubuntu.list
1 # deb https://private-ppa.launchpad.net/commercial-ppa-uploaders/intellij-idea-ce/ubuntu precise main #Added by software-center; credentials stored in /etc/apt/auth.conf
2 deb https://private-ppa.launchpad.net/commercial-ppa-uploaders/intellij-idea-ce/ubuntu precise main #Added by software-center; credentials stored in /etc/apt/auth.conf
/etc/apt/sources.list.d/webupd8team-sublime-text-3-precise.list
1 # deb http://ppa.launchpad.net/webupd8team/sublime-text-3/ubuntu precise main
2 deb-src http://ppa.launchpad.net/webupd8team/sublime-text-3/ubuntu precise main
/etc/apt/sources.list.d/typesafe-apt.list
1 # Typesafe repository.
2 deb http://apt.typesafe.com/ unicorn main # Typesafe "unicorn" releases.
/etc/apt/sources.list.d/eclipse-team-ppa-precise.list
1 deb http://ppa.launchpad.net/eclipse-team/ppa/ubuntu precise main
2 deb-src http://ppa.launchpad.net/eclipse-team/ppa/ubuntu precise main
/etc/apt/sources.list.d/medibuntu.list
1 ## Please report any bug on https://bugs.launchpad.net/medibuntu/
2 deb http://packages.medibuntu.org/ precise free non-free #Medibuntu - Ubuntu 12.04 "precise pangolin"
3 # deb-src http://packages.medibuntu.org/ precise free non-free #Medibuntu (source) - Ubuntu 12.04 "precise pangolin"
/etc/apt/sources.list.d/lezhoev-qstamina-precise.list
1 deb http://ppa.launchpad.net/lezhoev/qstamina/ubuntu precise main
2 deb-src http://ppa.launchpad.net/lezhoev/qstamina/ubuntu precise main
/etc/apt/sources.list.d/webupd8team-java-precise.list
1 deb http://ppa.launchpad.net/webupd8team/java/ubuntu precise main
2 deb-src http://ppa.launchpad.net/webupd8team/java/ubuntu precise main
/etc/apt/sources.list.d/tualatrix-ppa-precise.list
1 deb http://ppa.launchpad.net/tualatrix/ppa/ubuntu precise main
2 deb-src http://ppa.launchpad.net/tualatrix/ppa/ubuntu precise main
/etc/apt/sources.list.d/kilian-f_lux-precise.list
1 deb http://ppa.launchpad.net/kilian/f.lux/ubuntu precise main
2 deb-src http://ppa.launchpad.net/kilian/f.lux/ubuntu precise main
/etc/apt/sources.list.d/ubuntu-wine-ppa-precise.list
1 deb http://ppa.launchpad.net/ubuntu-wine/ppa/ubuntu precise main
2 deb-src http://ppa.launchpad.net/ubuntu-wine/ppa/ubuntu precise main
/etc/apt/sources.list.d/fsqcds-goldenddict-precise.list
1 deb http://ppa.launchpad.net/fsqcds/goldendict/ubuntu precise main
2 deb-src http://ppa.launchpad.net/fsqcds/goldendict/ubuntu precise main
/etc/apt/sources.list.d/webupd8team-rhythmbox-precise.list
1 deb http://ppa.launchpad.net/webupd8team/rhythmbox/ubuntu precise main
2 deb-src http://ppa.launchpad.net/webupd8team/rhythmbox/ubuntu precise main
/etc/apt/sources.list.d/upubuntu-com-devel-precise.list
1 deb http://ppa.launchpad.net/upubuntu-com/devel/ubuntu precise main
2 deb-src http://ppa.launchpad.net/upubuntu-com/devel/ubuntu precise main
我在以下位置遇到了另一个麻烦sudo apt-get update：
Err http://ppa.launchpad.net precise/main Sources
404 Not Found
Err http://ppa.launchpad.net precise/main amd64 Packages
404 Not Found
Err http://ppa.launchpad.net precise/main i386 Packages
404 Not Found
- 如何解决这个烦恼呢？
答案1
W: Failed to fetch http://ppa.launchpad.net/eclipse-team/ppa/ubuntu/dists/precise/main/binary-i386/Packages 404 Not Found
服务器上不存在该路径；显然，eclipse-teamppa 不提供 Ubuntu 12.04“精确”的软件包：
http://ppa.launchpad.net/eclipse-team/ppa/ubuntu/dists/
您可以通过删除该文件来解决此问题/etc/apt/sources.list.d/eclipse-team-ppa-precise.list：
sudo rm -f /etc/apt/sources.list.d/eclipse-team-ppa-precise.list