我从三月初开始使用 13.04 的开发版本。在开发版本中，运行该sudo apt-get update命令的一般行为是，如果列表文件已更改，则完全下载列表文件。而如果使用 Ubuntu 的稳定版本，则该命令只会下载列表文件的差异（如果列表文件已更改）（rsync 样式）。
基本上，开发版本sudo apt-get update会下载大约 17-18 MB 的数据；而稳定版本则仅下载大约 1 MB 的数据（初始运行除外）。
现在，由于 13.04 已作为稳定版本发布，我想更改的行为sudo apt-get update以模仿其在稳定版本中的正常行为。我该如何实现这一点？
之前在 Ask Ubuntu 上有人问过一个类似的问题，不过是针对稳定版本的：
然而，这是 12.04 中的一个错误，后来得到了修复。但那里给出的答案对我来说不可行。对于 Ubuntu+1 来说，这不是一个错误，而是开发版本的一般行为。无论如何，我会仔细阅读那里提供的答案：
John S Gruber 的回答
touch在运行命令之前询问相关文件（sudo apt-get update）每次。对我来说这绝对不可行。这个答案对于这个问题来说是可以的，因为它是 12.04 中的一个错误，并且它在这种情况下提供了一个临时修复。Chan-Ho Suh 的回答要求更改更新镜像。这无法解决开发版本中的问题。
安瓦尔的回答也是针对这种情况的临时解决方案。它假设我只会
sudo apt-get update在添加 PPA 后运行命令，因此要求禁用其他存储库。这对我来说是不可行的，因为我显然想更新所有存储库。我不一定只在添加 PPA 后运行此命令。我每天都会运行此命令来安装 Canonical 发布的任何更新。我用它来sudo apt-get update代替软件中心。
所以就是这样。我如何恢复sudo apt-get update命令的正常行为以仅下载已更改文件的差异？希望相同的解决方案也适用于软件中心，因为如果我使用它进行更新，软件中心也会消耗类似数量的带宽。
我绝对不想只是为了恢复这种行为而重新安装 13.04。
sudo apt-get update如果有重要影响，则输出：
$ sudo apt-get update
Hit http://dl.google.com stable Release.gpg
Hit http://dl.google.com stable Release
Hit http://ppa.launchpad.net raring Release.gpg
Hit http://dl.google.com stable/main i386 Packages
Hit http://linux.dropbox.com precise Release.gpg
Hit http://ppa.launchpad.net raring Release.gpg
Get:1 http://mirror.picosecond.org raring Release.gpg [933 B]
Hit http://ppa.launchpad.net raring Release
Hit http://linux.dropbox.com precise Release
Get:2 http://mirror.picosecond.org raring-updates Release.gpg [933 B]
Hit http://ppa.launchpad.net raring Release
Hit http://linux.dropbox.com precise/main i386 Packages
Hit http://ppa.launchpad.net raring/main i386 Packages
Get:3 http://mirror.picosecond.org raring-backports Release.gpg [933 B]
Ign http://dl.google.com stable/main Translation-en_IN
Ign http://dl.google.com stable/main Translation-en
Hit http://mirror.picosecond.org raring-security Release.gpg
Get:4 http://mirror.picosecond.org raring Release [40.8 kB]
Hit http://ppa.launchpad.net raring/main i386 Packages
Get:5 http://mirror.picosecond.org raring-updates Release [40.8 kB]
Get:6 http://mirror.picosecond.org raring-backports Release [40.8 kB]
Ign http://linux.dropbox.com precise/main Translation-en_IN
Ign http://linux.dropbox.com precise/main Translation-en
Hit http://mirror.picosecond.org raring-security Release
Get:7 http://mirror.picosecond.org raring/main Sources [963 kB]
Ign http://ppa.launchpad.net raring/main Translation-en_IN
Ign http://ppa.launchpad.net raring/main Translation-en
Ign http://ppa.launchpad.net raring/main Translation-en_IN
Ign http://ppa.launchpad.net raring/main Translation-en
Get:8 http://mirror.picosecond.org raring/restricted Sources [5,987 B]
Get:9 http://mirror.picosecond.org raring/universe Sources [5,838 kB]
Get:10 http://mirror.picosecond.org raring/multiverse Sources [171 kB]
Get:11 http://mirror.picosecond.org raring/main i386 Packages [1,168 kB]
Get:12 http://mirror.picosecond.org raring/restricted i386 Packages [9,623 B]
Get:13 http://mirror.picosecond.org raring/universe i386 Packages [5,405 kB]
Get:14 http://mirror.picosecond.org raring/multiverse i386 Packages [131 kB]
Hit http://mirror.picosecond.org raring/main Translation-en
Hit http://mirror.picosecond.org raring/multiverse Translation-en
Hit http://mirror.picosecond.org raring/restricted Translation-en
Get:15 http://mirror.picosecond.org raring/universe Translation-en [3,736 kB]
Get:16 http://mirror.picosecond.org raring-updates/main Sources [1,616 B]
Get:17 http://mirror.picosecond.org raring-updates/restricted Sources [14 B]
Get:18 http://mirror.picosecond.org raring-updates/universe Sources [14 B]
Get:19 http://mirror.picosecond.org raring-updates/multiverse Sources [14 B]
Get:20 http://mirror.picosecond.org raring-updates/main i386 Packages [3,331 B]
Get:21 http://mirror.picosecond.org raring-updates/restricted i386 Packages [14 B]
Get:22 http://mirror.picosecond.org raring-updates/universe i386 Packages [1,078 B]
Get:23 http://mirror.picosecond.org raring-updates/multiverse i386 Packages [14 B]
Hit http://mirror.picosecond.org raring-updates/main Translation-en
Hit http://mirror.picosecond.org raring-updates/multiverse Translation-en
Hit http://mirror.picosecond.org raring-updates/restricted Translation-en
Hit http://mirror.picosecond.org raring-updates/universe Translation-en
Get:24 http://mirror.picosecond.org raring-backports/main Sources [14 B]
Get:25 http://mirror.picosecond.org raring-backports/restricted Sources [14 B]
Get:26 http://mirror.picosecond.org raring-backports/universe Sources [738 B]
Get:27 http://mirror.picosecond.org raring-backports/multiverse Sources [14 B]
Get:28 http://mirror.picosecond.org raring-backports/main i386 Packages [14 B]
Get:29 http://mirror.picosecond.org raring-backports/restricted i386 Packages [14 B]
Get:30 http://mirror.picosecond.org raring-backports/universe i386 Packages [508 B]
Get:31 http://mirror.picosecond.org raring-backports/multiverse i386 Packages [14 B]
Hit http://mirror.picosecond.org raring-backports/main Translation-en
Hit http://mirror.picosecond.org raring-backports/multiverse Translation-en
Hit http://mirror.picosecond.org raring-backports/restricted Translation-en
Hit http://mirror.picosecond.org raring-backports/universe Translation-en
Hit http://mirror.picosecond.org raring-security/main Sources
Hit http://mirror.picosecond.org raring-security/restricted Sources
Hit http://mirror.picosecond.org raring-security/universe Sources
Hit http://mirror.picosecond.org raring-security/multiverse Sources
Hit http://mirror.picosecond.org raring-security/main i386 Packages
Hit http://mirror.picosecond.org raring-security/restricted i386 Packages
Hit http://mirror.picosecond.org raring-security/universe i386 Packages
Hit http://mirror.picosecond.org raring-security/multiverse i386 Packages
Hit http://mirror.picosecond.org raring-security/main Translation-en
Hit http://mirror.picosecond.org raring-security/multiverse Translation-en
Hit http://mirror.picosecond.org raring-security/restricted Translation-en
Hit http://mirror.picosecond.org raring-security/universe Translation-en
Ign http://mirror.picosecond.org raring/main Translation-en_IN
Ign http://mirror.picosecond.org raring/multiverse Translation-en_IN
Ign http://mirror.picosecond.org raring/restricted Translation-en_IN
Ign http://mirror.picosecond.org raring/universe Translation-en_IN
Ign http://mirror.picosecond.org raring-updates/main Translation-en_IN
Ign http://mirror.picosecond.org raring-updates/multiverse Translation-en_IN
Ign http://mirror.picosecond.org raring-updates/restricted Translation-en_IN
Ign http://mirror.picosecond.org raring-updates/universe Translation-en_IN
Ign http://mirror.picosecond.org raring-backports/main Translation-en_IN
Ign http://mirror.picosecond.org raring-backports/multiverse Translation-en_IN
Ign http://mirror.picosecond.org raring-backports/restricted Translation-en_IN
Ign http://mirror.picosecond.org raring-backports/universe Translation-en_IN
Ign http://mirror.picosecond.org raring-security/main Translation-en_IN
Ign http://mirror.picosecond.org raring-security/multiverse Translation-en_IN
Ign http://mirror.picosecond.org raring-security/restricted Translation-en_IN
Ign http://mirror.picosecond.org raring-security/universe Translation-en_IN
Fetched 17.6 MB in 3min 46s (77.7 kB/s)
Reading package lists... Done
/etc/apt/sources.list如有疑问，内容如下：
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://mirror.picosecond.org/ubuntu/ raring main restricted
deb-src http://mirror.picosecond.org/ubuntu/ raring main restricted
## Major bug fix updates produced after the final release of the
## distribution.
deb http://mirror.picosecond.org/ubuntu/ raring-updates main restricted
deb-src http://mirror.picosecond.org/ubuntu/ raring-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://mirror.picosecond.org/ubuntu/ raring universe
deb-src http://mirror.picosecond.org/ubuntu/ raring universe
deb http://mirror.picosecond.org/ubuntu/ raring-updates universe
deb-src http://mirror.picosecond.org/ubuntu/ raring-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 to
## 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://mirror.picosecond.org/ubuntu/ raring multiverse
deb-src http://mirror.picosecond.org/ubuntu/ raring multiverse
deb http://mirror.picosecond.org/ubuntu/ raring-updates multiverse
deb-src http://mirror.picosecond.org/ubuntu/ raring-updates multiverse
## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## 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://mirror.picosecond.org/ubuntu/ raring-backports main restricted universe multiverse
deb-src http://mirror.picosecond.org/ubuntu/ raring-backports main restricted universe multiverse
deb http://mirror.picosecond.org/ubuntu/ raring-security main restricted
deb-src http://mirror.picosecond.org/ubuntu/ raring-security main restricted
deb http://mirror.picosecond.org/ubuntu/ raring-security universe
deb-src http://mirror.picosecond.org/ubuntu/ raring-security universe
deb http://mirror.picosecond.org/ubuntu/ raring-security multiverse
deb-src http://mirror.picosecond.org/ubuntu/ raring-security multiverse
## Uncomment the following two lines to add software from Canonical's
## 'partner' repository.
## This software is not part of Ubuntu, but is offered by Canonical and the
## respective vendors as a service to Ubuntu users.
# deb http://archive.canonical.com/ubuntu raring partner
# deb-src http://archive.canonical.com/ubuntu raring partner
## Uncomment the following two lines to add software from Ubuntu's
## 'extras' repository.
## This software is not part of Ubuntu, but is offered by third-party
## developers who want to ship their latest software.
# deb http://extras.ubuntu.com/ubuntu raring main
# deb-src http://extras.ubuntu.com/ubuntu raring main
答案1
apt 实际上在开发版本和稳定版本之间并没有做任何不同的事情。
但是，版本本身停止变化，因此 apt 需要下载的软件包列表的大小变得更小。
我们以 Raring 为例。
在开发过程中，raring-updates和raring-security口袋仍然是空的，但raring口袋会定期（半小时）更新。
发布后，口袋停止变化。更新现在作为新包进入和口袋raring而上传。raring-updatesraring-security
从 apt 的角度来看，在开发过程中raring每次运行时都会完整下载软件包列表apt-get update（除非在上游更新之间的半小时内调用两次或更多次）。这是一个很大的列表，因此需要一些时间。
现在 Raring 已经发布，raring软件包列表不再变化。raring-updates和raring-security软件包列表确实会发生变化，但这些列表要小得多，因为它们只包含自 Raring 发布以来在 Raring 中发生“变化”的软件包。
我可以在你的问题的输出中看到这种行为。它看起来正如预期的那样：口袋raring刚刚打无需下载；得到raring-updates与raring-security实际下载量相对应。编辑：再次查看，似乎有些文件被不必要地重新下载；请参阅我的其他答案。
如果这对您来说太慢，请考虑使用更快的镜像，或删除那里相当大的 PPA 列表。如果您不需要可用的源，也可以删除deb-src中的行。sources.listapt-get
如果您直接安装此版本，我相信您不会看到任何不同的行为。
答案2
另一种可能是，您使用的镜像不保留时间戳，或者本地 apt 缓存损坏，导致 apt 每次重新下载镜像中实际上没有更改的文件。请尝试这个答案清除本地缓存，并切换到保留时间戳的镜像。