Question on Dependencies

[Derick Centeno]

Hi Bob:
A quick answer would be to refer you to the linux system itself.  You 
could do:

$man yum

or likewise

$man rpm

and you would get rather basic information which could be useful.  The 
key here is that rpm is an almost standard way of maintaining one 
package containing one application.
Dependencies really are independent programs which provide a function 
or other capability to a larger program which that larger program 
originally didn't have.  It is sometimes the case the different 
applications can share or use the same dependencies.  Like the larger 
application program, dependencies have their own programmers and 
designers which support just that.

If you took the time to read the description of yum or rpm provided in 
the man pages, you would see that yum itself utilizes rpm.  In a narrow 
sense, rpm is a dependency for yum itself.

What rpm does for one package or application or dependency -- yum can 
do for several dependencies and applications at one time -- at the same 
time.  yum receives instructions regarding where applications are from 
yum.conf and when yum.conf is correctly structured it allows yum to 
search find and install programs or dependencies where-ever they are 
found to exist first.  It is quite possible for one location to have an 
application, but not the dependency and another to have the dependency 
but not the application; yum sorts that information all out and 
collects whatever is needed arranging it in the correct order required 
by that application using a certain dependency (as some applications 
are so sensitive that they won't work unless the see the correct 
dependency at an exact order to be used for future processing at a 
precise point during the build process of that application) -- this is 
what yum figures out for you.  The speed it does this all at is 
affected by whether you use broadband or not.

However, given the complexity and how huge many programs are today, you 
can intuit that you would be using just rpm all day -- that is if you 
found all the correct dependencies and could place them in the correct 
sequence as you build an application into an executeable from it's 
source.  Yum on the other hand, shortens all that for you allowing you 
to have a chance of living a reasonable humane life.

Again yum tracks down for you all related dependencies an application 
needs, together with the application itself and installs them all 
together; when yum is finished you can run the application right then 
-- sometimes not even a reboot is necessary.   rpm cannot do all that, 
it is not required or expected to; however without rpm Linux would not 
have a common agreed upon means of package containment.

Best of Luck...

On Jun 13, 2006, at 4:34 AM, Bob Katz wrote:

> Hi
>          I have been trying to install packages with no luck the 
> biggest problem is when I try to run the rpm it states that I need a 
> package (dependencies) But when I run yum list installed it states 
> that I have that package installed on my disk 
>
>          This problem has happened 3-4 times already  why does the rpm 
> not see the package installed I don't get this 
>
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>   Thank You
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>                                                               
> Bob_______________________________________________