What does "require" actually mean?

[Michael Schwendt]

On Sat, 24 Aug 2013 10:43:10 +0100, Patrick O'Callaghan wrote:

> I thought I had a working understanding of yum and rpm, until I came
> across this:
> 
> # rpm -q --whatrequires libvdpau
> no package requires libvdpau
> # yum --assumeno erase libvdpau
> [snip]
> Transaction Summary
> ==============================================================================================================
> Remove  1 Package (+147 Dependent packages)
> ...
> 
> Why does yum want to remove 147 additional packages if none of them
> require libvdpau? (Note that I'm not asking about libvdpau specifically,
> it's just an example).

They don't require the package name "libvdpau", but contents of the
package. Run "rpm -e --test libvdpau" to display those dependencies.
The package may be renamed (or the contents moved to a different
package) without breaking the dependencies.

The repoquery tool can distinguish between --exactdeps and --alldeps
queries:

  $ repoquery --exactdeps --whatrequires libvdpau
  $

is similar to your "rpm -q --whatrequires libvdpau" query except that
it looks at repositories, too. The default is the --alldeps option,
which also takes into account what is provided by the package:

  $ repoquery --whatrequires libvdpau
  directfb-0:1.6.2-3.fc19.i686
  directfb-0:1.6.2-3.fc19.x86_64
  gstreamer-plugins-bad-free-0:0.10.23-19.fc20.i686
  gstreamer-plugins-bad-free-0:0.10.23-19.fc20.x86_64
  gstreamer-plugins-bad-free-extras-0:0.10.23-19.fc20.i686
  gstreamer-plugins-bad-free-extras-0:0.10.23-19.fc20.x86_64
  gstreamer1-plugins-bad-free-0:1.1.3-1.fc20.i686
  gstreamer1-plugins-bad-free-0:1.1.3-1.fc20.x86_64
  libva-vdpau-driver-0:0.7.4-6.fc20.i686
  libva-vdpau-driver-0:0.7.4-6.fc20.x86_64
  libvdpau-devel-0:0.7-1.fc20.i686
  libvdpau-devel-0:0.7-1.fc20.x86_64
  mesa-vdpau-drivers-0:9.2-0.15.20130723.fc20.x86_64
  vdpauinfo-0:0.0.6-7.fc20.x86_64

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