Re: dynamic dependency check

[Scot Mc Pherson <scot linuxfromscratch org>]

On Tuesday 20 January 2004 12:29 am, Dhanvi K wrote:
> Hi,
>
>      I would like my spec file to dynamically pick up rpm requirements
> depending on the OS on which the RPM is being installed. for e.g. If the
> RPM is being installed on Fedora box, then the spec should pick up one
> set of dependency rpms, while if its installing on a RedHat Enterprise
> box,  then it should pick up another set of RPMS.
>
>      I would like to know whether and how this is possible in the spec
> file ? Thanks for your time and advice
Yes this is possible, though it requires that the OS variation be declared in 
some standard format by the OS...it is "often" found in /etc/. Though there 
is no standard format. One could use a structure to discover various points 
of interest on the operating system, but discovering with something is 
fedora, redhat, debian, slackware, and their various versions. And then one 
needs to consider user modified systems.

Generally speaking...and I do say generally...the most important things to 
know are the kernel type and version, and libc type and version. All the 
other dependencies are really far too many to try and track/monitor with a 
spec file. The best thing to do is to make your spec file look for the 
various "differences" in pieces.  Use the %ifarch and %ifos directives. You 
can also use shell scriptlets for a great deal of your logic system. But 
again you are looking at a lot of work. One of the best soiurces of 
inspiration and consequentially also dispair are teh xfree86 spec files that 
mharris has developed. They cover a lot of system detection ground and may be 
of some help.

But be ready for the fact that you aren't really going to be able to cover 
ever single instance without developing and maintaining the one single spec 
file becoming a full time job as you try to keep up with all the changing 
systems. Worry instead about covering standards and creating a standards 
compliant spec file. Allow users to "customize" the spec files for their 
needs instead. Keeping things simple will make things easier on your users, 
trying to cover every possibility will make things harder for you, and will 
also make things harder for your users when they DO find they must customize 
your spec file to work for their system.  Not everyone is system builder, and 
not everyone has the patience to dig through a complex logic structure.

Scot

>
> Regards,
> Dhanvi.
>
>
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