apt sources.list 在升级到 12.04 时被禁用

Question

在 do-release-upgrade 之后，我现在正在运行 ubuntu 12.04 LTS，如下所示

> lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 12.04 LTS
Release:        12.04
Codename:       precise

但是，我发现 /etc/apt/sources.list 中的所有条目都被注释掉了，只有一个除外。

问题：在下面显示的内容中，将旧的“清晰”替换为“精确”对我来说是否安全？

## unixteam source list
# deb http://debian.yorku.ca/ubuntu/ precise main main/debian-installer restricted restricted/debian-installer # disabled on upgrade to precise
# deb-src http://debian.yorku.ca/ubuntu/ precise main restricted # disabled on upgrade to precise
# deb http://debian.yorku.ca/ubuntu/ lucid-updates main restricted # disabled on upgrade to precise
# deb-src http://debian.yorku.ca/ubuntu/ lucid-updates main restricted # disabled on upgrade to precise

# deb http://debian.yorku.ca/ubuntu/ precise universe # disabled on upgrade to precise
# deb-src http://debian.yorku.ca/ubuntu/ precise universe # disabled on upgrade to precise

# deb http://debian.yorku.ca/ubuntu/ precise multiverse # disabled on upgrade to precise
# deb-src http://debian.yorku.ca/ubuntu/ precise multiverse # disabled on upgrade to precise

# deb http://debian.yorku.ca/ubuntu lucid-security main restricted # disabled on upgrade to precise
# deb-src http://debian.yorku.ca/ubuntu lucid-security main restricted # disabled on upgrade to precise
# deb http://debian.yorku.ca/ubuntu lucid-security universe # disabled on upgrade to precise
# deb-src http://debian.yorku.ca/ubuntu lucid-security universe # disabled on upgrade to precise
# deb http://debian.yorku.ca/ubuntu lucid-security multiverse # disabled on upgrade to precise
# deb-src http://debian.yorku.ca/ubuntu lucid-security multiverse # disabled on upgrade to precise
# R sources
# see http://cran.us.r-project.org/bin/linux/ubuntu/ for details
# deb http://probability.ca/cran/bin/linux/ubuntu lucid/ # disabled on upgrade to precise
deb http://archive.ubuntu.com/ubuntu precise main multiverse universe

Answer 1

安装Y PPA Manager mate，它非常直观：http://www.webupd8.org/2012/10/y-ppa-manager-0092-released-with-new.html

Answer 2

检查源是否确实支持precise 我检查了此源[ http://debian.yorku.ca/ubuntu/dists/ ]并且有一个precise文件夹，因此将源重命名为precise应该可以正常工作。尽管在已标记的源上，lucid-security您可能希望将它们更改为precise-security.