Question about the package dependencies, etc.

FreePeter · n00b Joined: 21 Jan 2008 Posts: 12

First about revdep-rebuild, in gentoo document, it says

This tool is Gentoo's Reverse Dependency rebuilder. It will scan your installed ebuilds to find packages that have become broken as a result of an upgrade of a package they depend on. It can emerge those packages for you but it can also happen that a given package does not work anymore with the currently installed dependencies, in which case you should upgrade the broken package to a more recent version. revdep-rebuild will pass flags to emerge which lets you use the --pretend flag to see what is going to be emerged again before you go any further.

And I wondered when using other Linux distributions like Ubuntu, I didn't know such tools,
So how is other distributions to solve such problems?

And another problem is about libexpat
Recently I update the portage(the package, not the portage tree~), I use -NuD, so it update many libraries.
After all it told me that libexpat.so.0 is no longer existing and I need to fix it by using redvep-rebuild.
And I found it a very old topic : https://forums.gentoo.org/viewtopic-t-575655.html

As I understands, it's because when we update the libexpat(to libexpat.so.1), the old version(i.e. libexpat.so.0) is removed, so some softwares rely on the old version won't rebuild automatically (and need we run revdep-rebuild manually)
So I wondered, why can't we hold some different versions of the same lib co-exist for some time?
If I haven't mistaken, Ubuntu will reserve some different versions of the same lib (like xxx.so.1, xxx.so.2...?)
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The Sun Also Rises.

NeddySeagoon · Posted: Sat Feb 16, 2008 6:46 pm Post subject:

FreePeter,

Binary distros get around the problem by hiding it from users, the binary distro builders (thats you for Gentoo) solve the problem when they make the next version of the distro.

libexpat was a particular problem. Gentoo provides a feature called SLOTs.
This allows several versions of a package to be installed at the same time but you can only use one version at a time.
Look at gcc for example