我刚刚在一台新电脑上安装了 Ubuntu 10.04。我试图在上面安装一个我需要的应用程序（我的旧电脑坏了，我必须把它送去维修）。我设法安装了 texlive，但其他的都无法安装了。我想要安装的所有软件都是我之前在旧电脑上成功安装的软件（使用相同版本的 Ubuntu）。我不明白为什么终端会给出这个警告（抱歉，终端说一半英语，一半波兰语，但我希望这足够了）：
maria@marysia-ubuntu:~$ sudo aptitude install emacs
Czytanie list pakietów... Gotowe
Budowanie drzewa zależności
Odczyt informacji o stanie... Gotowe
Reading extended state information
Initializing package states... Gotowe
The following NEW packages will be installed:
emacs emacs23{a} emacs23-bin-common{a} emacs23-common{a}
emacsen-common{a}
0 packages upgraded, 5 newly installed, 0 to remove and 0 not upgraded.
Need to get 23,9MB of archives. After unpacking 73,8MB will be used.
Do you want to continue? [Y/n/?] Y
WARNING: untrusted versions of the following packages will be installed!
Untrusted packages could compromise your system's security.
You should only proceed with the installation if you are certain that
this is what you want to do.
emacs emacs23-bin-common emacsen-common emacs23-common emacs23
Do you want to ignore this warning and proceed anyway?
To continue, enter "Yes"; to abort, enter "No"
我也尝试安装其他编辑器，结果相同。当我决定确保要安装的软件包是安全的时，我最终输入了“是”。安装成功结束，但编辑器不理解 .tex 文件（而 .tex 文件本身是安全的）：
this is pdfTeX, Version 3.1415926-1.40.10 (TeX Live 2009/Debian)
restricted \write18 enabled.
entering extended mode
(./Szarfi.tex
! Undefined control sequence.
l.2 \documentclass
{book}
?
而且，我意识到 Synaptic Manager 中没有任何标记为受 Canonical 支持的软件包......
有什么建议吗？提前致谢。
附言
使用前请确认 apt 源update：
maria@marysia-ubuntu:~$ cat /etc/apt/sources.list
#deb cdrom:[Ubuntu 10.04.2 LTS _Lucid Lynx_ - Release i386 (20110211.1)]/ lucid main restricted
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://pl.archive.ubuntu.com/ubuntu/ lucid main restricted
deb-src http://pl.archive.ubuntu.com/ubuntu/ lucid main restricted
## Major bug fix updates produced after the final release of the
## distribution.
deb http://pl.archive.ubuntu.com/ubuntu/ lucid-updates main restricted
deb-src http://pl.archive.ubuntu.com/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://pl.archive.ubuntu.com/ubuntu/ lucid universe
deb-src http://pl.archive.ubuntu.com/ubuntu/ lucid universe
deb http://pl.archive.ubuntu.com/ubuntu/ lucid-updates universe
deb-src http://pl.archive.ubuntu.com/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 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://pl.archive.ubuntu.com/ubuntu/ lucid multiverse
deb-src http://pl.archive.ubuntu.com/ubuntu/ lucid multiverse
deb http://pl.archive.ubuntu.com/ubuntu/ lucid-updates multiverse
deb-src http://pl.archive.ubuntu.com/ubuntu/ lucid-updates multiverse
## Uncomment the following two lines to add software from the 'backports'
## repository.
## 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://pl.archive.ubuntu.com/ubuntu/ lucid-backports main restricted universe multiverse
# deb-src http://pl.archive.ubuntu.com/ubuntu/ lucid-backports main restricted universe 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 lucid partner
# deb-src http://archive.canonical.com/ubuntu lucid partner
deb http://security.ubuntu.com/ubuntu lucid-security main restricted
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
maria@marysia-ubuntu:~$
使用后update，一切几乎正常。我成功安装了 3 个应用程序（texlive、texworks 和 ekg），Synaptic 显示“Cannonical 支持”的图标。但连接问题仍然存在。
我已连接到互联网，可以使用聊天，但有时无法打开任何网页。我不确定这是否是同一问题的一部分，或者其中一个问题是否已解决，而另一个问题我应该写一篇单独的帖子。
使用更新后的 apt 源列表：
maria@marysia-ubuntu:~$ cat /etc/apt/sources.list
#deb cdrom:[Ubuntu 10.04.2 LTS _Lucid Lynx_ - Release i386 (20110211.1)]/ lucid main restricted
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://pl.archive.ubuntu.com/ubuntu/ lucid main restricted
deb-src http://pl.archive.ubuntu.com/ubuntu/ lucid main restricted
## Major bug fix updates produced after the final release of the
## distribution.
deb http://pl.archive.ubuntu.com/ubuntu/ lucid-updates main restricted
deb-src http://pl.archive.ubuntu.com/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://pl.archive.ubuntu.com/ubuntu/ lucid universe
deb-src http://pl.archive.ubuntu.com/ubuntu/ lucid universe
deb http://pl.archive.ubuntu.com/ubuntu/ lucid-updates universe
deb-src http://pl.archive.ubuntu.com/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 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://pl.archive.ubuntu.com/ubuntu/ lucid multiverse
deb-src http://pl.archive.ubuntu.com/ubuntu/ lucid multiverse
deb http://pl.archive.ubuntu.com/ubuntu/ lucid-updates multiverse
deb-src http://pl.archive.ubuntu.com/ubuntu/ lucid-updates multiverse
## Uncomment the following two lines to add software from the 'backports'
## repository.
## 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://pl.archive.ubuntu.com/ubuntu/ lucid-backports main restricted universe multiverse
# deb-src http://pl.archive.ubuntu.com/ubuntu/ lucid-backports main restricted universe 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 lucid partner
# deb-src http://archive.canonical.com/ubuntu lucid partner
deb http://security.ubuntu.com/ubuntu lucid-security main restricted
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
maria@marysia-ubuntu:~$
似乎有所改变，但这是我唯一能理解的事情。
谢谢。
答案1
尝试更新数据库
sudo apt-get update
如果此后你仍看到警告消息，请提供你的存储库列表
grep -IRH '^deb ' /etc/apt/
答案2
如果您刚刚安装了 Ubuntu，并且没有添加任何存储库，请更新软件包列表并升级软件包：
sudo apt-get update
sudo apt-get upgrade
建议在安装其他软件包之前先更新系统（至少在第一次安装后）。 CD 的内容可能已过时。
答案3
我不是 100% 确定，但看起来您缺少一些 gpg 密钥。为了解决这个问题，我会安装 launchpad-getkeys，它将导入您系统上所有缺少的密钥。
要安装 launchpad-getkeys，您需要先添加一个 ppa -什么是 ppa 以及如何使用它们ppa 线是ppa:nilarimogard/webupd8
然后你可以安装 launchpad-get keys 首先输入这个
sudo apt-get update
然后这个
sudo apt-get install launchpad-getkeys
最后用这个命令运行
sudo launchpad-getkeys
最后，在导入密钥后，我将运行另一次更新。
sudo apt-get update
希望这可以帮助