将整个系统升级到 Sid 后，我遇到了一些 NVidia 驱动程序问题，不得不重新安装。但我注意到一些 VLC 依赖项在 NVidia 卸载过程中丢失了。果然，VLC 不再存在。我无法从 Sid、Stable 和 Videolan 自己的 PPA 安装 VLC。
现在，每次我尝试重新安装 VLC 时，都会收到以下输出：
The following packages have unmet dependencies:
vlc : Depends: vlc-l10n (= 3.0.0~rc4-2) but it is not going to be installed
Depends: vlc-plugin-base (= 3.0.0~rc4-2) but it is not going to be installed
Recommends: vlc-plugin-notify (= 3.0.0~rc4-2) but it is not going to be installed
Recommends: vlc-plugin-samba (= 3.0.0~rc4-2) but it is not going to be installed
Recommends: vlc-plugin-skins2 (= 3.0.0~rc4-2) but it is not going to be installed
Recommends: vlc-plugin-video-splitter (= 3.0.0~rc4-2) but it is not going to be installed
Recommends: vlc-plugin-visualization (= 3.0.0~rc4-2) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
并且：
$ sudo apt install vlc=2.2.7-1~deb9u1
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
vlc : Depends: vlc-bin (= 2.2.7-1~deb9u1) but 3.0.0~rc4-2 is to be installed
Depends: vlc-plugin-base (= 2.2.7-1~deb9u1) but it is not going to be installed
Depends: vlc-plugin-qt (= 2.2.7-1~deb9u1) but 3.0.0~rc4-2 is to be installed
Depends: vlc-plugin-video-output (= 2.2.7-1~deb9u1) but 3.0.0~rc4-2 is to be installed
Recommends: vlc-plugin-notify (= 2.2.7-1~deb9u1) but it is not going to be installed
Recommends: vlc-plugin-samba (= 2.2.7-1~deb9u1) but it is not going to be installed
Recommends: vlc-plugin-skins2 (= 2.2.7-1~deb9u1) but it is not going to be installed
Recommends: vlc-plugin-video-splitter (= 2.2.7-1~deb9u1) but it is not going to be installed
Recommends: vlc-plugin-visualization (= 2.2.7-1~deb9u1) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
如果我尝试以递归方式逐个安装，则会在任何地方都找不到特定的包版本。
目前我的缓存策略是这样的：
vlc:
Installed: (none)
Candidate: 3.0.0~rc4-2
Version table:
3.0.0~rc4-2 500
500 http://ftp.us.debian.org/debian sid/main amd64 Packages
2.2.7-1~deb9u1 500
500 http://ftp.us.debian.org/debian stretch/main amd64 Packages
500 http://security.debian.org/debian-security stretch/updates/main amd64 Packages
2.2.2+git20170721+r59033+56~ubuntu16.04.1 500
500 http://ppa.launchpad.net/videolan/stable-daily/ubuntu xenial/main amd64 Packages
这是我的sources.list：
# deb cdrom:[Official Debian GNU/Linux Live 9.3.0 xfce 2017-12-09T13:26]/ sid main
deb http://ftp.us.debian.org/debian/ sid main non-free contrib
deb-src http://ftp.us.debian.org/debian/ sid main non-free contrib
deb http://ftp.us.debian.org/debian/ stretch main non-free contrib
deb-src http://ftp.us.debian.org/debian/ stretch main non-free contrib
deb http://security.debian.org/debian-security stretch/updates main contrib non-free
deb-src http://security.debian.org/debian-security stretch/updates main contrib non-free
# stretch-updates, previously known as 'volatile'
deb http://ftp.us.debian.org/debian/ stretch-updates main contrib non-free
deb-src http://ftp.us.debian.org/debian/ stretch-updates main contrib non-free
更多内容sources.list.d：
deb http://ppa.launchpad.net/videolan/stable-daily/ubuntu xenial main
deb-src http://ppa.launchpad.net/videolan/stable-daily/ubuntu xenial main
如果我尝试安装 PPA 版本：
$ sudo apt install vlc=2.2.2+git20170721+r59033+56~ubuntu16.04.1
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
vlc : Depends: vlc-nox (= 2.2.2+git20170721+r59033+56~ubuntu16.04.1) but it is not going to be installed
Depends: libavcodec-ffmpeg56 (>= 7:2.4) but it is not installable or
libavcodec-ffmpeg-extra56 (>= 7:2.4) but it is not installable
Depends: libavutil-ffmpeg54 (>= 7:2.4) but it is not installable
Depends: libgles1-mesa (>= 7.8.1) but it is not going to be installed or
libgles1
Depends: libvlccore8 (>= 2.2.0) but it is not going to be installed
Recommends: vlc-plugin-notify (= 2.2.2+git20170721+r59033+56~ubuntu16.04.1) but it is not going to be installed
Recommends: vlc-plugin-samba (= 2.2.2+git20170721+r59033+56~ubuntu16.04.1) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
然后我也尝试了：
$ sudo apt install vlc-nox=2.2.2+git20170721+r59033+56~ubuntu16.04.1
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
vlc-nox : Depends: libavcodec-ffmpeg56 (>= 7:2.4) but it is not installable or
libavcodec-ffmpeg-extra56 (>= 7:2.4) but it is not installable
Depends: libavformat-ffmpeg56 (>= 7:2.4) but it is not installable
Depends: libavutil-ffmpeg54 (>= 7:2.4) but it is not installable
Depends: libchromaprint0 (>= 0.2) but it is not installable
Depends: libjpeg8 (>= 8c) but it is not installable
Depends: liblivemedia50 but it is not installable
Depends: libpng12-0 (>= 1.2.13-4) but it is not installable
Depends: libpostproc-ffmpeg53 (>= 7:2.4) but it is not installable
Depends: libschroedinger-1.0-0 (>= 1.0.10) but it is not installable
Depends: libsidplay2v5 but it is not installable
Depends: libswscale-ffmpeg3 (>= 7:2.4) but it is not installable
Depends: libvlccore8 (>= 2.2.0) but it is not going to be installed
Depends: libx265-79 (>= 1.9) but it is not installable
E: Unable to correct problems, you have held broken packages.
我确实尝试过：
sudo apt update
sudo apt upgrade
sudo apt clean
sudo apt autoclean
sudo apt autoremove
很多很多次。
答案1
我通过完全卸载 NVidia 驱动程序、安装 VLC 然后重新安装 NVidia 解决了自己的问题。不确定这两件事有什么关系。