Build-time and runtime dependencies

[lars_the_bear]

Hi folks

When I look at the dependency tree for, say, 'vim', I see dependencies on git, python, perl, ruby, and autoconf. So far as I know, vim does not require any of these things at runtime. I'm guessing that some of these are build-time dependencies, needed to build that package from source.

Would these things still get installed if I installed the binary release, rather than building from source?

I note that, right now, 'git' is not on my system, despite being a dependency of 'vim', which is. Is this because it got removed in a clean-up operation? If there is a difference between build-time and runtime dependences, does that difference affect cleanup?

If 'git' was installed when I installed 'vim', can I prevent it being cleaned up, if I actually want to use it?

Sorry if this is inarticulate -- I'm just trying to understand how things work.

BR, Lars

[xgivolari]

Ebuilds can declare different kinds of dependencies:

DEPEND: these need to be found at build time (e.g. libraries)

BDEPEND: programs that need to be executed at build time (e.g. pkgconf)

RDEPEND: required at runtime

PDEPEND: required at runtime, may be merged after the the package requiring it.

For binary packages, only RDEPEND and PDEPEND are satisfied. If you want to merge build time dependencies for a binary package as well, you can do so with the emerge argument "--with-bdeps=y"

For more information, check out the Dependencies article of the Gentoo development guide.

To find out what kind of dependency an ebuild declares, you can use "qdepends -v" (part of app-portage/portage-utils). E.g. for vim:

[xgivolari]

If you query dependencies with equery g, it lists all possible dependencies. However, vim for example only depends on ruby if you enable its ruby USE-flag. Because this flag is not enabled by default, a binary package of vim will not pull in ruby. AFAICT, the only case where vim depends on git is if you build it from a live ebuild (i.e. vim-9999). In that case it is a dependency of git-r3.eclass, which is the eclass that handles building packages from git branches or commits.

[lars_the_bear]

Thanks.

This is much more complicated than I expected it to be, and I expected it to be complicated

BR, Lars

[Hu]

How exactly are you looking at the dependency tree? As described above, there are many subtleties, and different tools may provide different levels of explanation.

[lars_the_bear]