aptitude safe-upgrade vs apt-get upgrade.

[Ram Ramesh]

Hi,

  I am trying to upgrade the current setup and I am unable to
understand the differences between aptitude vs. apt-get usage.
When I do apt-get -s upgrade, I get

myth2 [rramesh] 100 > sudo apt-get -s upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
  gstreamer1.0-gl gstreamer1.0-plugins-bad gstreamer1.0-plugins-base
  gstreamer1.0-plugins-good gstreamer1.0-plugins-ugly libasound2-plugins
  libavcodec58 libavformat58 libavresample4 libavutil56 libchromaprint1
  libgstreamer-gl1.0-0 libgstreamer-plugins-bad1.0-0
  libgstreamer-plugins-base1.0-0 libswresample3 libswscale5
linux-image-amd64
  mythtv-frontend
0 upgraded, 0 newly installed, 0 to remove and 18 not upgraded.

Clearly nothing is  going to be done. However aptitude -s safe-upgrade
shows that it will install these.

myth2 [rramesh] 101 > sudo aptitude -s safe-upgrade
Resolving dependencies...
  libcdio19{a} libfaac0{a} libfdk-aac2{a} libilbc2{a} libkvazaar4{a}
  liblrdf0{a} libmfx1{a} libopenh264-5{a} libx264-157{a} libx265-176{a}
  linux-image-4.19.0-12-amd64{a}
  libcdio18{u} libcrystalhd3{u} libssh-gcrypt-4{u} libvpx5{u}
  libx264-155{u} libx265-165{u}
  gstreamer1.0-gl gstreamer1.0-plugins-bad gstreamer1.0-plugins-base
  gstreamer1.0-plugins-good gstreamer1.0-plugins-ugly libasound2-plugins
  libavcodec58 libavformat58 libavresample4 libavutil56 libchromaprint1
  libgstreamer-gl1.0-0 libgstreamer-plugins-bad1.0-0
  libgstreamer-plugins-base1.0-0 libswresample3 libswscale5
  linux-image-amd64
17 packages upgraded, 11 newly installed, 6 to remove and 1 not upgraded.
Need to get 72.9 MB of archives. After unpacking 270 MB will be used.
Note: Using 'Simulate' mode.
Do you want to continue? [Y/n/?]
Would download/install/remove packages.

This makes me wonder if it is better to use aptitude over apt-get. Why
these differences?  What is the correct way to maintain a working system
and still keep the system up to date.

Regards
Ramesh

[Joe]

On Sun, 25 Oct 2020 12:12:19 -0500

Post by Ram Ramesh
Hi,
  I am trying to upgrade the current setup and I am unable to
understand the differences between aptitude vs. apt-get usage.
When I do apt-get -s upgrade, I get

myth2 [rramesh] 100 > sudo apt-get -s upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
  gstreamer1.0-gl gstreamer1.0-plugins-bad gstreamer1.0-plugins-base
  gstreamer1.0-plugins-good gstreamer1.0-plugins-ugly
libasound2-plugins libavcodec58 libavformat58 libavresample4
libavutil56 libchromaprint1 libgstreamer-gl1.0-0
libgstreamer-plugins-bad1.0-0 libgstreamer-plugins-base1.0-0
libswresample3 libswscale5 linux-image-amd64
  mythtv-frontend
0 upgraded, 0 newly installed, 0 to remove and 18 not upgraded.

Clearly nothing is  going to be done. However aptitude -s
safe-upgrade shows that it will install these.

myth2 [rramesh] 101 > sudo aptitude -s safe-upgrade
Resolving dependencies...
  libcdio19{a} libfaac0{a} libfdk-aac2{a} libilbc2{a} libkvazaar4{a}
  liblrdf0{a} libmfx1{a} libopenh264-5{a} libx264-157{a}
libx265-176{a} linux-image-4.19.0-12-amd64{a}
  libcdio18{u} libcrystalhd3{u} libssh-gcrypt-4{u} libvpx5{u}
  libx264-155{u} libx265-165{u}
  gstreamer1.0-gl gstreamer1.0-plugins-bad gstreamer1.0-plugins-base
  gstreamer1.0-plugins-good gstreamer1.0-plugins-ugly
libasound2-plugins libavcodec58 libavformat58 libavresample4
libavutil56 libchromaprint1 libgstreamer-gl1.0-0
libgstreamer-plugins-bad1.0-0 libgstreamer-plugins-base1.0-0
libswresample3 libswscale5 linux-image-amd64
17 packages upgraded, 11 newly installed, 6 to remove and 1 not
upgraded. Need to get 72.9 MB of archives. After unpacking 270 MB
will be used.
Note: Using 'Simulate' mode.
Do you want to continue? [Y/n/?]
Would download/install/remove packages.

This makes me wonder if it is better to use aptitude over apt-get.
Why these differences?  What is the correct way to maintain a working
system and still keep the system up to date.

To begin with, which distribution is it? In general, with Stable, it
pretty much doesn't matter which tool is used. The kind of problems you
have indicate Unstable or Testing.

First, apt is pretty much apt-get, with different syntax and a few
extra features. Aptitude can generally do a better job of resolving
'difficult' dependencies, but if used with a great many packages (>100)
is likely to be very slow. With more than about 500 packages to deal
with, it may grind to a halt. Don't use it on an Unstable which hasn't
been upgraded for six months. Don't use it for a version upgrade of
Stable, unless the release notes for the upgrade explicitly recommend
it.

Synaptic, the GUI tool, is a front end to apt-get. All the apt tools
are a front end to dpkg, which does all the work but does no dependency
checking and is therefore not safe to be used directly.

All of the tools have a 'safe' mode which is guaranteed not to remove
packages. However, many upgrades do require the removal of some
packages, so the safe mode will only get you so far in these cases.

If you are using Stable, there should never be any real problem in
upgrading. With Testing or Unstable, problems do occur, and you need to
be willing to understand and solve them. Generally, if you keep the
system up to date regularly, aptitude will usually do a good job.

With Unstable or Testing, it is often the case that new versions of a
few packages from a large related set become available before the rest.
The new packages will be mostly incompatible with the existing set, so
upgrading them will cause the removal of some of the rest of the set,
along with other applications which depend on them. If you see that
half your applications are about to be removed, say 'no'. If you do
this with apt-get or apt in safe mode, then packages will be 'held
back'. Aptitude full-upgrade will usually give you a number of options,
with decreasing numbers of removals proposed. If you keep declining
options, it will eventually get to 'keep everything as it is', but you
may find one of the options worth doing.

Generally time will sort this problem out, as the rest of the set is
released. It is usually possible to upgrade some packages which do not
include the problem ones. This can be done with any of the tools, but
on a graphical system I prefer Synaptic. Other methods may involve a lot
of typing.

[Andrei POPESCU]

Post by Joe
Synaptic, the GUI tool, is a front end to apt-get. All the apt tools
are a front end to dpkg, which does all the work but does no dependency
checking and is therefore not safe to be used directly.

dpkg does its own dependency checking, in addition to APT (the software,
not the command), and will prevent any inconsistencies unless you use
one of the --force switches.

In my opinion this is pretty safe ;)

APT, aptitude and others are more than just front ends to dpkg as they
are also the ones working with your configured repositories.

Post by Joe
All of the tools have a 'safe' mode which is guaranteed not to remove
packages. However, many upgrades do require the removal of some
packages, so the safe mode will only get you so far in these cases.
If you are using Stable, there should never be any real problem in
upgrading.

'apt-get upgrade' is insufficient even on a stable system, e.g. due to
the kernel package changing names, it's better to just use 'apt upgrade'
(or 'aptitude safe-upgrade') instead.

Kind regards,
Andrei

[John Hasler]

Post by Andrei POPESCU
dpkg does its own dependency checking, in addition to APT (the
software, not the command), and will prevent any inconsistencies
unless you use one of the --force switches.

What it does not do is resolve dependencies. Apt recursively resolves
dependencies, installing them as required. It also detects conflicts
and offers to resolve them as well as breaking loops.

Dpkg is safe but can be rather frustrating.

[Andrei POPESCU]

Post by John Hasler

Post by Andrei POPESCU
dpkg does its own dependency checking, in addition to APT (the
software, not the command), and will prevent any inconsistencies
unless you use one of the --force switches.

What it does not do is resolve dependencies. Apt recursively resolves
dependencies, installing them as required. It also detects conflicts
and offers to resolve them as well as breaking loops.

dpkg can only work with the set of .deb files that were passed on the
command line.

If all dependencies are included (or already installed), fine, otherwise
it will bail out as it doesn't (by design) have the capability to search
for them in repositories and download them (if this is what you mean by
resolving).

I believe someone demonstrated quite recently on list that dpkg has some
limits in the number and/or combination of packages it can deal with at
once, so APT might have to pass them in smaller chunks and/or specific
order (in case of Pre-Depends: maybe?).

Post by John Hasler
Dpkg is safe but can be rather frustrating.

As far as I'm concerned it does just fine what it was designed to do.

Kind regards,
Andrei

[David Wright]

Post by Andrei POPESCU

Post by John Hasler

Post by Andrei POPESCU
dpkg does its own dependency checking, in addition to APT (the
software, not the command), and will prevent any inconsistencies
unless you use one of the --force switches.

What it does not do is resolve dependencies. Apt recursively resolves
dependencies, installing them as required. It also detects conflicts
and offers to resolve them as well as breaking loops.

dpkg can only work with the set of .deb files that were passed on the
command line.
If all dependencies are included (or already installed), fine, otherwise
it will bail out as it doesn't (by design) have the capability to search
for them in repositories and download them (if this is what you mean by
resolving).
I believe someone demonstrated quite recently on list that dpkg has some
limits in the number and/or combination of packages it can deal with at
once, so APT might have to pass them in smaller chunks and/or specific
order (in case of Pre-Depends: maybe?).

Post by John Hasler
Dpkg is safe but can be rather frustrating.

As far as I'm concerned it does just fine what it was designed to do.

Years ago, I used to do mega installs with dpkg, copying the contents
of /var/cache/apt/archives/ from one machine onto a caddy, and then
installing them all on another.

I'm probably the person who recently demonstrated dpkg's (in)ability
to cleanly install 1558 packages simultaneously without help:

https://lists.debian.org/debian-user/2020/07/msg00032.html
(its References are all dead links because they fall in the previous month.)

This followed a demonstration of apt-get's reversibility:
specifying 271 "top-level" packages that resulted in 1558 being
installed altogether, and all 1558 being cleanly purged again.

Cheers,
David.

[Andrei POPESCU]

Post by David Wright

Post by Andrei POPESCU
I believe someone demonstrated quite recently on list that dpkg has some
limits in the number and/or combination of packages it can deal with at
once, so APT might have to pass them in smaller chunks and/or specific
order (in case of Pre-Depends: maybe?).

Post by John Hasler
Dpkg is safe but can be rather frustrating.

As far as I'm concerned it does just fine what it was designed to do.

Years ago, I used to do mega installs with dpkg, copying the contents
of /var/cache/apt/archives/ from one machine onto a caddy, and then
installing them all on another.
I'm probably the person who recently demonstrated dpkg's (in)ability
https://lists.debian.org/debian-user/2020/07/msg00032.html
(its References are all dead links because they fall in the previous month.)

Indeed, this is the experiment I was thinking of.

Post by David Wright
specifying 271 "top-level" packages that resulted in 1558 being
installed altogether, and all 1558 being cleanly purged again.

Somehow I'm still under the impression that this is supposed to work
with dpkg only.

You might want to post your findings to debian-dpkg for further
investigation.

Kind regard,
Andrei

[Michael Lange]

Hi,

On Sun, 25 Oct 2020 17:53:16 -0500
"R. Ramesh" <***@verizon.net> wrote:

(...)

Nothing fancy. Installed debian 10 from USB and added multi-media and
installed mythfrontend. That is all I have done.
This is a NUC Pentium (N3700) box and not fancy at all.  Here is my
kernel

(...)

My apt-get/aptitude output showed clear differences between the two.
So, I am not convinced about your claim that they should do the same
thing on a stable release unless stable release itself was broken when
installing with debian-10.6.0-amd64-netinst.iso.

it looks like what happens here is that the upgrade would replace
installed versions of multimedia related packages from buster with those
from deb-multimedia. Obviously apt-get and aptitude do not agree how to
handle this situation. Installing those packages requires obviously to
replace for example libcdio18 with libcdio19, which apt-get won't do with
the "apt-get upgrade" command.
I believe that most likely the root of the problem is, that no
apt-pinning rule is defined for the deb-multimedia repo.

To resolve this, you might consider to create a file
like e.g. /etc/apt/preferences.d/multimedia .

Here the content of that file looks like:

Package: *
Pin: release o=Unofficial Multimedia Packages,n=buster
Pin-Priority: 332

Package: *
Pin: release o=Unofficial Multimedia Packages,n=buster-backports
Pin-Priority: 331

with the respective entries in my sources.list:

deb http://www.deb-multimedia.org buster main non-free
deb http://www.deb-multimedia.org buster-backports main non-free

This should ensure that no such "accidental" upgrades will occur.

Regards

Michael

.-.. .. ...- . .-.. --- -. --. .- -. -.. .--. .-. --- ... .--. . .-.

Lots of people drink from the wrong bottle sometimes.
-- Edith Keeler, "The City on the Edge of Forever",
stardate unknown

[Michael Lange]

Hi,

On Mon, 26 Oct 2020 11:58:18 -0500
"R. Ramesh" <***@verizon.net> wrote:

(...)

I have these exact lines in my sources.list also. I thought we have
backports so that we can get the newer version of packages. For
example, buster multimedia has mythtv 0.30 and backports has mythtv
0.31 (the last time I checked). I have installed 0.31 in my system
(using -t stable-backports, I think) as my frontend need to be
compatible with backend that runs mythtv 0.31 (on xubuntu 20.04). In
that case, would the above pinning rule prevent proper upgrade as it
puts backports at a lower priority? (I assume that is what your pinning
rules imply unless priorities are increased with lower numerical value)
In other words, should I stick to aptitude's decision?
Why priority 331 and 332? Why not some other two with same
relationship? Sorry, if I asked a simple question. I will be more than
happy to read documentation, if I will find it there.

these values are somewhat arbitraryly chosen. The point is that they
have to be values smaller than 500 and greater than 100 and that the
value for the deb-multimedia backports needs to be smaller than that of
the regular deb-multimedia repo.

This is because 500 is the default priority of any repo defined in
sources.list; if two or more packages from different repos share this
same priority, the package with the newest version number will be
installed; usually when using stable with deb-multimedia this is the
deb-multimedia (backports) package. If priorities differ, the package with
the highest priority will be installed, unless the lower priority package
is explicitely requested by the user.

So, if you don't pin down the priority of deb-multimedia, virtually every
audio- and video-related package on your system will be replaced with the
deb-multimedia version, which for the sake of stability is very likely a
bad idea.
So it is safer to lower the priority of deb-multimedia and that of
deb-multimedia backports even a bit more, so that the official debian
packages remain the default, deb-multimedia packages the first
alternative if you actually want/need a newer version or a version with
some extra features and deb-multimedia backports the last choice if you
really, really need that version.

But please beware: blindly installing too many of these can easily mess
with apt's dependencies and cause nasty situations ("dependency hell")

In other words, should I stick to aptitude's decision?

I really recommend to do the pinning first, then re-run

$ apt update

and then look again what is suggested when you call apt-get upgrade or
aptitude safe-upgrade.
I have a hunch that probably there won't be much to upgrade anymore.

And as someone else pointed out, apt-get upgrade will not always install
the latest kernel and possibly other things you would want to keep up to
date, so you might wnat to consider to just use apt-get dist-upgrade
instead, which in my experience with a properly configured debian stable
system should not cause any problems.


Regards

Michael


.-.. .. ...- . .-.. --- -. --. .- -. -.. .--. .-. --- ... .--. . .-.

You're too beautiful to ignore. Too much woman.
-- Kirk to Yeoman Rand, "The Enemy Within", stardate
unknown