What does "require" actually mean?

[Patrick O'Callaghan]

On Sat, 2013-08-24 at 12:16 +0200, Michael Schwendt wrote:
> 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:

[snip]

OK, all becomes clear, thanks.

poc