Back up the UbuntuLucid source list

For other Ubuntu versions, you only need to change the release code "lucid" to "natty", "maverick", and "etc". For example, you need to change the release code to "natty", "maverick", and "etc". Several public keys are required.

For other Ubuntu versions, you only need to change the release code "lucid", for example, natty, maverick, etc.

There are several public keys required in: http://www.linuxidc.net/thread-2223-1-1.html

The VirtualBox source uses this method to add the Public key: wget-q http://download.virtualbox.org/virtualbox/debian/Oracle_vbox.asc-O-| sudo apt-key add-

#
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade
# Newer versions of the distribution.

Deb http://mirrors.ustc.edu.cn/ubuntu/ lucid main restrictd
Deb-src http://mirrors.ustc.edu.cn/ubuntu/ lucid main restrictd

# Major bug fix updates produced after the final release of
# Distribution.
Deb http://mirrors.ustc.edu.cn/ubuntu/ lucid-updates main restricted
The deb-src http://mirrors.ustc.edu.cn/ubuntu/ lucid-updates main restricted

# N. B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
# Team. Also, please note that software in universe will not receive any
# Review or updates from the Ubuntu security team.
Deb http://mirrors.ustc.edu.cn/ubuntu/ lucid universe
Deb-src http://mirrors.ustc.edu.cn/ubuntu/ lucid universe
Deb http://mirrors.ustc.edu.cn/ubuntu/ lucid-updates universe
Deb-src http://mirrors.ustc.edu.cn/ubuntu/ lucid-updates universe

# N. B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
# Team, and may not be under a free licence. Please satisfy yourself as
# Your rights to use the software. Also, please note that software in
# Multiverse will not receive any review or updates from the Ubuntu
# Security team.
Deb http://mirrors.ustc.edu.cn/ubuntu/ lucid multiverse
Deb-src http://mirrors.ustc.edu.cn/ubuntu/ lucid multiverse
Deb http://mirrors.ustc.edu.cn/ubuntu/ lucid-updates multiverse
Deb-src http://mirrors.ustc.edu.cn/ubuntu/ lucid-updates multiverse

# Uncomment the following lines to add software from the 'proposed'
# Respository.
# Deb http://mirrors.ustc.edu.cn/ubuntu/ lucid-proposed main restricted universe multiverse
# Deb-src http://mirrors.ustc.edu.cn/ubuntu/ lucid-proposed main restricted universe multiverse

# Uncomment the following two lines to add software from the 'backports'
# Repository.
# N. B. software from this repository may not have been tested
# Extensively as that contained in the main release, although it except des
# Newer versions of some applications which may provide useful features.
# Also, please note that software in backports will not receive any review
# Or updates from the Ubuntu security team.
# Deb http://mirrors.ustc.edu.cn/ubuntu/ lucid-backports main restricted universe multiverse
# Deb-src http://mirrors.ustc.edu.cn/ubuntu/ lucid-backports main restricted universe multiverse

# Uncomment the following two lines to add software from Canonical's
# 'Parter' repository.
# This software is not part of Ubuntu, but is offered by Canonical and
# Respective vendors as a service to Ubuntu users.
Deb http://archive.canonical.com/lucid partner
Deb-src http://archive.canonical.com/lucid partner

# Uncomment the following two lines to add software from the 'security'
# Repository.
Deb http://mirrors.ustc.edu.cn/ubuntu/ lucid-security main restricted
The deb-src http://mirrors.ustc.edu.cn/ubuntu/ lucid-security main restricted

Deb http://mirrors.ustc.edu.cn/ubuntu/ lucid-security universe
Deb-src http://mirrors.ustc.edu.cn/ubuntu/ lucid-security universe
Deb http://mirrors.ustc.edu.cn/ubuntu/ lucid-security multiverse
Deb-src http://mirrors.ustc.edu.cn/ubuntu/ lucid-security multiverse.

# Virtualbox
Deb http://download.virtualbox.org/virtualbox/debian lucid contrib non-free

# Valac PPA (vala-team)
Deb http://ppa.launchpad.net/vala-team/ubuntu/ lucid main

# Ibus-1.3 PPA (ibus-dev)
Deb http://ppa.launchpad.net/ibus-dev/ibus-1.3-lucid/ubuntu/ lucid main

#
# Sources from main servers.

Deb http://archive.ubuntu.com/ubuntu/ lucid main restricted
Deb-src http://archive.ubuntu.com/ubuntu/ lucid main restricted

Deb http://archive.ubuntu.com/ubuntu/ lucid-updates main restricted
The deb-src http://archive.ubuntu.com/ubuntu/ lucid-updates main restricted

Deb http://archive.ubuntu.com/ubuntu/ lucid universe
Deb-src http://archive.ubuntu.com/ubuntu/ lucid universe
Deb http://archive.ubuntu.com/ubuntu/ lucid-updates universe
Deb-src http://archive.ubuntu.com/ubuntu/ lucid-updates universe

Deb http://archive.ubuntu.com/ubuntu/ lucid multiverse
Deb-src http://archive.ubuntu.com/ubuntu/ lucid multiverse
Deb http://archive.ubuntu.com/ubuntu/ lucid-updates multiverse
Deb-src http://archive.ubuntu.com/ubuntu/ lucid-updates multiverse

# Deb http://archive.ubuntu.com/ubuntu/ lucid-proposed main restricted universe multiverse
# Deb-src http://archive.ubuntu.com/ubuntu/ lucid-proposed main restricted universe multiverse

# Deb http://archive.ubuntu.com/ubuntu/ lucid-backports main restricted universe multiverse
# Deb-src http://archive.ubuntu.com/ubuntu/ lucid-backports main restricted universe multiverse

Deb http://security.ubuntu.com/ubuntu/ lucid-security main restricted
The deb-src http://security.ubuntu.com/ubuntu/ lucid-security main restricted

Deb http://security.ubuntu.com/ubuntu/ lucid-security universe
Deb-src http://security.ubuntu.com/ubuntu/ lucid-security universe
Deb http://security.ubuntu.com/ubuntu/ lucid-security multiverse
Deb-src http://security.ubuntu.com/ubuntu/ lucid-security multiverse.