Hello Christian, > My guess is that in your previous attempt you added experimental to > your sources.list but didn't pin the release to a negative number, so > other packages might have automatically crept in in some cases, > screwing up your system that way. But if you pin experimental to a > negative number, you have to explicitly pin those packages that you > want back to a positive number in order for APT to consider them as > candidates for your system.
Actually, even though I implicated it, I never installed experimental stuff on my system. And "Pining" is not "Pinning" -- I learned the latter word from you and the former one from Monty Python (the sketch with the dead parrot). "Pining for s.th." means something like "desiring deeply (in a heartfelt way)". What I _did_ do prior to said trauma was [!!!KIDS, DONT TRY THIS AT HOME!!!]: Add deb http://www.deb-multimedia.org jessie main non-free to my /etc/apt/sources.list and then bray apt-get update apt-get upgrade The effects were akin to what I imagine may happen if you simply set your whole system to experimental. Hundreds of packages were pulled in and, for instance, sound was broken. Having /home separated from the rest of the system and only just come from another distro I decided it was simplest to reinstall. This was last Christmas and I have been happy ever since, successfully avoiding even 'testing'. To the issue: My acute Qt problem is solved since I finally found I could install Qt 5.4 locally in home and then have CMake find it setting the CMAKE_PREFIX_PATH accordingly (i.e. in my case to "/home/kochmn/sw/Qt/Qt_5_4/5.4/gcc_64/lib/cmake/Qt5Widgets" the Widgets package pulling in all other dependencies). I will keep "pinning" and the "apt-cache policy" in mind though and come back to your mails when I ever need a specific testing/experimental package without being ready to flame up my whole system. Thanks again to you and all others answering my question! Cheers, Markus. P.S.: I already unsubscribed from this mailing list again because I felt it was really spamming my mailbox with lots of stuff I did not even understand what people are talking about. Is there a way to configure it thus that it only forwards answers to the user's own posts to that user's mailbox? On 02.05.2015 16:57, Christian Seiler wrote: > On 05/02/2015 04:00 PM, Markus-Hermann Koch wrote: >> thanks for your detailed answer! >> >> Sigh. I am still hoping to avoid experimental on this one (being >> already traumatized from past experiences culminating in complete >> reinstallation into my now clean 'unstable' system with its single >> media package libdvdcss2). > > Well, if you do pin experimental packages to -1 by default, APT will > never install them, even if you ask it to. > > For example, if I want to install libkf5config-dev (only in > experimental so far), have experimental in my sources.list.d but also > pinned to -1, using APT has the following result: > > # apt-get install libkf5config-dev > Reading package lists... Done > Building dependency tree > Reading state information... Done > Package libkf5config-dev is not available, but is referred to by another > package. > This may mean that the package is missing, has been obsoleted, or > is only available from another source > > E: Package 'libkf5config-dev' has no installation candidate > > This means that no packages from experimental can be installed by > default, you have to explicitly pin them again to make certain packages > installable. > > On my own box, I did exactly the steps I wrote in my previous mail to > test the installation of Qt 5.4 (I'm running Jessie, Qt5 previously not > installed at all), and running apt-get install qt5-default it installed > Qt5 packages from experimental, but all other packages from Jessie. > > This works now because Qt 5.4 doesn't have any dependencies on stuff > that's only in experimental, so you will currently get ONLY Qt 5.4, but > everything else will be from other suits. > > Now, if at some point you want to install something from experimental > that does have additional deps on other experimental packages, you will > have the following stuff happen: > > - first you just pin the packages you want themselves to 500 > - then you try to install them with APT. that will tell you that it > can't resolve dependencies (and it will also tell you which ones) > - then you take a look at the dependencies you'd need from experimental > and see if you think you can live with that - if so, just add them > to the list of packages pinned to 500 (if you pin by releaese, you > can add the deps to the same list as the original package, if you pin > by version, you need to create a new block with the new version > number) > > My guess is that in your previous attempt you added experimental to your > sources.list but didn't pin the release to a negative number, so other > packages might have automatically crept in in some cases, screwing up > your system that way. But if you pin experimental to a negative number, > you have to explicitly pin those packages that you want back to a > positive number in order for APT to consider them as candidates for your > system. > >> Still: If I can make your priority based updating work and if it >> does not require pulling too important other testing/experimental >> libraries into my system I will give it a shot. > > As I said: currently Qt 5.4 is installable without any deps on stuff > that's not already in unstable. > > > If you understand what pinning does (and what different priority ranges > mean), then you can use that to selectively install packages from > different suits / different repositories without having the risk that > other packages from those repositories 'contaminate' your system. You > only have to keep in mind that 'apt-cache policy' is your friend if APT > complains about stuff, because with that you can check what's going on. > > Christian > -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: https://lists.debian.org/5545bcdf.9030...@markuskoch.eu
