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I'd like to install libqt5qmlmodels5 from packages.ubuntu.com.
The library exists in [universe] for [groovy] [hirsute] [impish].
I'm on Ubuntu 20.04.2 LTS [focal], so apt install doesn't work.

Can I still install the library?

I looked at "Download Source Package", and there are many things there.
Do I copy and paste the files found in the fileslist (where do I get those files from)?
What's the conincal way to install this library being on focal?

Trevor Hickey
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  • If you look at the first link you provided, specifically all the depends you'll note they need to be upgraded as well; which of course means all their respective depends also need upgrading.. ie. your focal system won't be focal anymore, so if you upgrade to the groovy package your system will become groovy and you'll no longer be using the LTS release of Qt5, no longer using the ... etc. and you'll need to backport patches for those packages yourself as you'll be using an unsupported group of packages. Upgrading your system is easiest & safest. (same applies with hirsute etc) – guiverc Aug 19 '21 at 01:51
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    Does this answer your question? Why don't the Ubuntu repositories have the latest versions of software? – guiverc Aug 19 '21 at 01:54
  • Your other alternative is to find a different form of whatever you need it for (ie. a snap or flatpak etc packaged version of whatever you end-use case is, so the requirement is provided inside a container and doesn't impact your base Ubuntu LTS system that uses LTS libraries/toolkits etc) Ubuntu 20.04 uses the 5.12.8 or LTS release of Qt5, not the later non-LTS Qt versions (they are available in the non-LTS releases) – guiverc Aug 19 '21 at 01:56
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    This sounds like an XY Problem. I can't imagine a scenario where someone would think they needed a particular version of a library with no other context behind it. As mentioned above by @guiverc, what you are proposing might break your system. I suggest that you ask about and provide details about the actual problem that you are experiencing. Otherwise you might get help with what you asked and end up not solving your actual problem, and spawning new ones on top of it all. – Nmath Aug 19 '21 at 02:25
  • That's what I was afraid of. I'm literally just missing libQt5QmlModels.so to link against. It would seem silly to upgrade an entire operating system or recursively upgrade packages to get it. Thank you for clarifying this. Maybe I can find it and build from source instead. In response to the XY Problem, I just want to build a qt application from a github project I found. It fails to build with /usr/bin/ld.gold: error: cannot find -lQt5QmlModel. I'm thinking if I have what I need to link against, I can build the application. I was looking for a non-evasive way of achieving that. – Trevor Hickey Aug 19 '21 at 02:25
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    "I just want to build a qt application from a github project I found. It fails to build with /usr/bin/ld.gold: error: cannot find -lQt5QmlModel" - This is the question you should be asking about and the one you should be providing more details about. You should probably ask a new question. Tell us which project, link to it, and give us all of the steps you've taken with all the output. Things you should consider: is the project still maintained? Are there instructions from the developers? Can you build the project in a VM or other container so as to not damage your installed system? – Nmath Aug 19 '21 at 02:48

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Manually installing an Ubuntu package from an older release may or may not work, and is, in any case, not supported. Sometimes, an older package installs without any issue, but more frequently, there are conflicts with the required dependencies not matching these present or available in the newer Ubuntu version.

You can take over and manually try to fix dependencies yourself, but only take over package management if you have extremely good technical linux skills. However, if you are of that caliber, a far better approach is grabbing source code and compiling yourself.

vanadium
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  • In this case it will not work - libqt5qmlmodels5 : Depends: libqt5core5a (>= 5.14.1) but 5.12.8+dfsg-0ubuntu1 is to be installed – N0rbert Aug 19 '21 at 07:07