是的，没有其他解决方案如何安装 Pantheon 桌面环境？对于较旧版本的 Ubuntu 来说，这是可行的。唯一一个在更新时不会显示“404 未找到”的 ppa 是 ppa:elementary-os/daily，但我无法安装 elementary-desktop，因为它只是说（在控制台中）它不会安装与其相关的软件包。
The following packages have unmet dependencies:
elementary-desktop : Depends: ubuntu-extras-keyring but it is not installed
Recommends: apport-hooks-elementary but it is not going to be installed
Recommends: bluez-gstreamer but it is not going to be installed
Recommends: elementary-default-settings but it is not going to be installed
Recommends: elementary-os-prerelease but it is not going to be installed
Recommends: fonts-elementary-core but it is not going to be installed
Recommends: gcalctool but it is not going to be installed
Recommends: geary but it is not going to be installed
Recommends: ginn but it is not going to be installed
Recommends: gtksourceview-3.0-theme-solarized-elementary but it is not installed
Recommends: ibus-pinyin
Recommends: light-locker but it is not going to be installed
Recommends: pantheon-greeter but it is not going to be installed
Recommends: plymouth-theme-elementary but it is not going to be installed
Recommends: plymouth-theme-elementary-text but it is not going to be installed
Recommends: print-test-page-elementary but it is not installed
Recommends: pulseaudio-module-gconf but it is not going to be installed
Recommends: switchboard but it is not going to be installed
Recommends: switchboard-gnome-control-center-override but it is not going to be installed
Recommends: switchboard-plug-about but it is not going to be installed
Recommends: switchboard-plug-applications but it is not going to be installed
Recommends: switchboard-plug-datetime but it is not going to be installed
Recommends: switchboard-plug-display but it is not going to be installed
Recommends: switchboard-plug-gcc-bluetooth but it is not going to be installed
Recommends: switchboard-plug-gcc-color but it is not going to be installed
Recommends: switchboard-plug-gcc-mouse but it is not going to be installed
Recommends: switchboard-plug-gcc-network but it is not going to be installed
Recommends: switchboard-plug-gcc-printer but it is not going to be installed
Recommends: switchboard-plug-gcc-sound but it is not going to be installed
Recommends: switchboard-plug-gcc-ua but it is not going to be installed
Recommends: switchboard-plug-gcc-users but it is not going to be installed
Recommends: switchboard-plug-gcc-wacom but it is not going to be installed
Recommends: switchboard-plug-keyboard but it is not going to be installed
Recommends: switchboard-plug-locale but it is not going to be installed
Recommends: switchboard-plug-notifications but it is not installed
Recommends: switchboard-plug-online-accounts but it is not going to be installed
Recommends: switchboard-plug-pantheon-shell but it is not going to be installed
Recommends: switchboard-plug-power but it is not going to be installed
Recommends: switchboard-plug-security-privacy but it is not going to be installed
Recommends: ttf-punjabi-fonts but it is not going to be installed
Recommends: tumbler-plugins-extra but it is not going to be installed
Recommends: user-specific-alternatives but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
答案1
我已经设法通过在我的系统上本地重建 ubuntu-extras-keyring 来安装基本桌面，如下所示：
mkdir somedir; cd somedir
sudo apt-get install -y debhelper
wget http://archive.ubuntu.com/ubuntu/pool/main/u/ubuntu-extras-keyring/ubuntu-extras-keyring_2010.09.27.{tar.gz,dsc}
tar -xf *.tar.gz
cd ubuntu-extras-keyring-2010.09.17
debuild -i -us -uc -b
sudo dpkg -i ../ubuntu-extras-keyring_2010.09.27_all.deb
之后，elementary-desktop将会安装，但最后会出错，因为它取决于systemd-shim哪个不再需要或不再想要，而 15.04 具有完整的 SystemD 实现。
当出现错误时，运行
sudo dpkg --force-depends -r indicator-datetime
sudo apt-get purge unity-control-center unity-control-center-signon
这样就完成安装。
我希望在不久的将来，Elementary 的人们能够修复他们的存储库以正确处理 SystemD - Ubuntu 15.04 转移到 SystemD 是在正式发布前几周完成的，Elementary 的人可能没有时间去适应这一点。
安装后，您可以注销并在显示管理器的会话列表中看到“Pantheon”，但如果您尝试登录，您只会看到蓝图纸样式的 Elementary“测试版壁纸”。问题是会话启动了 Slingshot 和 Gala，但没有启动 WingPanel 或 Plank。目前，我使用 Slingshot 的ALT-F2快捷方式打开启动器并手动运行 Plank 和 WingPanel（只需输入全部小写的名称并按 ENTER 键）。