[CentOS] RPM `requires` installation order

Thu Oct 29 09:46:01 UTC 2015
Nicolas Thierry-Mieg <Nicolas.Thierry-Mieg at imag.fr>

On 10/29/2015 01:56 AM, Shyam S wrote:
> Hello All,
> I'm a bit of newbie with rpm/yum, seeking the help from rpm/yum experts.
> Suppose I have an RPM package A which depends on package B.
> RPM A's spec has 'Requires:B'  tag with 'autoprov' and 'autoreq' enabled.
> When I install RPM A on a 'centos 6.5' machine with 'RPM version 4.8.0',
> using the command `yum install A` :
> * `rpm` installs A first, then it installs B.
> * The installation of B could partially fail. That is, A would installed
> even if the       installation of the dependency, B has failed.
> Is this the expected behaviour? (Shouldn't B be installed before A?)

AFAIK yum performs installs and updates as atomic operations, ie in your 
case if installing B fails yum will also roll back the install of A.
Doesn't it?

> Can the same behaviour be expected across versions (such as el5)?
> I was hoping that the dependencies would be installed before the main
> package is installed. Which would prevent the installation of the main
> package, If one of the dependencies failed to install.
> I have tried `PreReq` tag as well, which has same behaviour as far as I can
> tell.
> Is there any other means to accomplish my requirement?