Re: How to get out of a "...but it is not going to be installed"-type situation with apt-get?

[Kynn Jones <kynnjo@gmail.com>]

On Sat, Dec 19, 2015 at 10:24 AM, Kynn Jones <kynnjo@gmail.com> wrote:
> I apologize for all these apt-related questions.
>
> I have rtfm'd on this ad nauseam.  For years, literally.
>
> Still, I'm routinely rendered utterly helpless by this sort of thing:
>
>     % sudo apt-get -qq update
>     % sudo apt-get -qq upgrade
>     % sudo apt-get -qq dist-upgrade
>     % sudo apt-get install ffmpeg
>     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:
>      ffmpeg : Depends: libavcodec-ffmpeg56 (>= 7:2.7) but it is not
> going to be installed or
>                        libavcodec-ffmpeg-extra56 (>= 7:2.7) but it is
> not going to be installed
>               Depends: libavdevice-ffmpeg56 (>= 7:2.6) but it is not
> going to be installed
>               Depends: libavfilter-ffmpeg5 (>= 7:2.4) but it is not
> going to be installed
>               Depends: libavformat-ffmpeg56 (>= 7:2.6) but it is not
> going to be installed
>     E: Unable to correct problems, you have held broken packages.
>
>
> Where does one begin troubleshooting out such problems?
>
> Thanks in advance for any help.
>
> kj
>
>
> PS:
>
>     # /etc/apt/apt.conf
>     APT::Default-Release "jessie";
>
>     # /etc/apt/preferences
>     Package: /^r-/
>     Pin: release n=stretch
>     Pin-Priority: 995
>
>     # /etc/apt/sources.list
>     deb http://http.us.debian.org/debian jessie main contrib non-free
>     deb http://http.us.debian.org/debian jessie-updates main contrib
>     deb http://security.debian.org jessie/updates main contrib non-free
>     deb-src http://http.us.debian.org/debian jessie main contrib
>     deb-src http://http.us.debian.org/debian jessie-updates main contrib
>     deb-src http://security.debian.org jessie/updates main contrib non-free
>
>     deb http://http.us.debian.org/debian stretch main contrib non-free
>     deb-src http://http.us.debian.org/debian stretch main contrib
>
>     deb http://download.videolan.org/pub/debian/stable /  # needed for
> libdvdcss2 (see http://www.videolan.org/developers/libdvdcss.html)
>
> I have made no changes to my /etc/apt/apt.conf.d/,
> /etc/apt/preferences.d, and /etc/apt/sources.list.d/ that I'm aware
> of.  The last two of these directories are empty.  The first one
> contains
>
>     % ls -l /etc/apt/apt.conf.d
>     -rw-rw-r-- 1 root root   82 Nov 22 13:45 00CDMountPoint
>     -rw-rw-r-- 1 root root   40 Nov 22 13:45 00trustcdrom
>     -rw-rw-r-- 1 root root  643 Nov 22 13:45 01autoremove
>     -rw-r--r-- 1 root root  981 Dec 19 09:44 01autoremove-kernels
>     -rw-rw-r-- 1 root root  243 Nov 22 13:45 20dbus
>     -rw-rw-r-- 1 root root  141 Nov 22 13:45 20listchanges
>     -rw-rw-r-- 1 root root 1040 Nov 22 13:45 20packagekit
>     -rw-rw-r-- 1 root root 3945 Nov 22 13:45 50unattended-upgrades
>     -rw-rw-r-- 1 root root  182 Nov 22 13:45 70debconf



An additional detail I noticed after I posted the message above:

    % apt-cache policy ffmpeg
    ffmpeg:
      Installed: (none)
      Candidate: 7:2.8.3-1
      Version table:
         7:2.8.3-1 0
            500 http://http.us.debian.org/debian/ stretch/main amd64 Packages


I don't understand why the ffmpeg version from stretch comes out as
the best (and only remaining) candidate.

How can I find out why the ffmpeg version from jessie (whatever that
is) is not a candidate?


TIA,

kj