edit yum config file

[Derick Centeno]

Hi Bob:
I have a different approach regarding yum.conf, if you are willing to  
consider it.

First, here is my yum.conf file which I use within YDL 4.1.  Yes, it  
works very well and it is not broken nor does it point to broken links,  
mirrors or other dead ends:

[main]
cachedir=/var/cache/yum
debuglevel=2
logfile=/var/log/yum.log
pkgpolicy=newest
distroverpkg=yellowdog-release
tolerant=1
exactarch=1
obsoletes=1

[base]
name=Yellow Dog Linux 4.1 Base
baseurl=http://ftp.yellowdoglinux.com/pub/yellowdog/yum/4.1/base/
baseurl=http://ydl.osuosl.org/yum/4.1/base/
#baseurl=http://mirror.ac.uk/mirror/ftp.yellowdoglinux.com/yum/4.1/base/

[updates]
name=Yellow Dog Linux 4.1 Updates
baseurl=http://ftp.yellowdoglinux.com/pub/yellowdog/yum/4.1/update/
baseurl=http://ydl.osuosl.org/yum/4.1/updates/
#baseurl=http://mirror.ac.uk/mirror/ftp.yellowdoglinux.com/yum/4.1/ 
updates/

[extras]
name=Yellow Dog Linux 4.1 Extras
baseurl=http://ftp.yellowdoglinux.com/pub/yellowdog/yum/4.1/extras/
baseurl=http://ydl.osuosl.org/yum/4.1/extras/
#baseurl=http://http:mirror.ac.uk/mirror/ftp.yellowdoglinux.com/yum/ 
4.1/extras/

[update]
name=Yellow Dog Linux 4.1 Update
baseurl=http://ydl.osuosl.org/yum/4.1/update/
#baseurl=http://mirror.ac.uk/mirror/ftp.yellowdoglinux.com/yum/4.1/ 
update/


Now for the exciting part, once you learn to read/write and modify  
yum.conf to any mirror you can then include any other location which  
holds data which yum can understand.  This also means that unless yum  
becomes surpassed or replaced by something better, once you learn what  
is here in this note you'll be able to use yum well for perpetuity --  
for any future version of YDL or other Linux which also utilizes yum in  
a similar fashion.

Another thing to remember is that yum is constructed to make  
installation, upgrade and removal of packages a wee bit easier; it is  
optimized to function within one range of a version of YDL at a time.   
Within that range of one version of YDL say YDL 3-3.0.1 -- yum will  
find packages and dependencies which are designed and similar enough so  
that any improvements along the way work well together.  But a jump  
from YDL 3 to YDL 4.0 is too big a gap -- there are too many very  
different changes to nearly all applications and dependencies.  The gap  
of developmental change between YDL 4.0 and YDL 4.1 is even wider.  It  
is easy to be misled by the numbers believe that there is only a .1  
variation difference between YDL 4.1 and YDL 4.0; engineers, God bless  
them, don't think at all like the rest of us.

This is not the best or most useful means to explain all the  
differences between YDL 4.0 and YDL 4.1.  Although I am not an  
engineer, I do know the nuances of developmental changes of at least  
one tool used throughout several versions of YDL and I could easily  
produce a Master's thesis 15 pages thick on just that one tool  
discussing it's different capabilities in each version of YDL up to YDL  
4.1.  Essentially that means three versions of that same thesis - one  
for YDL 3.0, for YDL 4.0, and for YDL 4.1 - each report comprising 15  
pages discussing the unique variations uniquely addressing just those  
versions of YDL.  Even if this program weren't used in YDL, it would be  
used in other Linux distributions, and the same challenge would exist  
there.  In other words, discussing the vast sea of changes for one  
program is enormous work.  The same program over different versions of  
one distribution may not look different in function to the basic user;  
but those persons more deeply involved in programming and technical  
design where control of computer hardware is critical -- these persons  
will notice that commands are different, flexibility of functions are  
improved and other nuances.  Now, consider that -- in fact -- not only  
one program has been modified, improved or corrected between one  
version of YDL to another, but nearly all?

It has been said that a "little knowledge is a dangerous thing".

This difficulty is evident in how yum and associated programs like yum  
are applied.  It is possible for you or anyone to learn enough to  
really mess-up your computer so that you have not only different  
versions of YDL running but different versions of the same program  
available to be invoked and run.  This is a bad thing, as the whole  
point of development -- the intention of all engineers across all  
distributions of Linux is that when a better version of a program has  
been demonstrated to work sufficiently well then that tool is available  
for distribution for that particular version of Linux when it is  
available.  yum will "see" it when the mirrors have updated the  
information yum refers to whenever you run as superuser:

# yum check-update

If something is available, yum will tell you.  It's that simple.  Now.   
It didn't use to be.  Why not take advantage of this?  If yum "sees"  
something is available for update within a particular version of YDL --  
it will tell you in understandable detail... well enough to get an idea  
of what that item is anyway.  Then decide whether you wish to install  
it:

# yum install _____________

where the _______ represents whatever the name of that program you care  
to have installed within the particular version of yum.

Other persons using older computer systems need components or programs  
which are no longer supported or provided in modern versions of YDL;  
there are good reasons why earlier versions of YDL or other  
distributions remain available to assist them.  Still improvements and  
changes continue within Linux and Linux tools.  However, it is unique  
to Linux and Unix that programs can still be run which were being run  
in the 1970s!  It is not impossible to keep current even when using old  
computers or old versions of Linux.
One needs however, to pay attention and learn enough details so that  
one can prolong the usefulness of the computer one prefers to use.

You Bob, however, have a G5 (I referred back to my own email records),  
there is no reason to for you to use any earlier incarnation of YDL or  
any other Linux distribution at all.  You should only use YDL 4.1 and  
forward, and yum should be set accordingly.  Even if you decide to move  
towards another Linux distribution, don't move backwards -- move  
forwards.

Linux is great that way, and amongst the Linux distributions -- YDL is  
very reliable.

Now to the "good" stuff.

If you notice how yum.conf is written you'll notice that the URL is  
written as a definition for the variable baseurl.
In other words, if you recall your high school algebra the word  
"baseurl" is acting exactly like the variable x in a typical algebra  
equation.
The URL itself is the location of where yum resides in that mirror.

Let's suppose I don't know where a particular version of YDL is but I  
do know where YDL mirrors are supposed to be.  Here's the location of  
YDL mirrors:

http://www.terrasoftsolutions.com/resources/ftp_mirrors.shtml

Now in that list I find: http://ydl.oregonstate.edu

But when I click upon it, I find myself at:

http://ydl.osuosl.org

was there a mistake?  No, there wasn't.  What happened here was that  
the institution changed the name of their servers.
Now on that page there are a list of folders, I chose the folder for  
yum because I'm looking for the information which yum needs to refer  
to.
Next I see that there are a variety of folders which yum can refer to;  
as I am thinking that you have the G5 (which I wish I had) your yum  
should exclusively be pointing to 4.1, therefore I select 4.1.  This  
takes me deeper into that area of the server, and if you pay attention  
to the URL of your browser you'll see that your location changes as  
well.

At this level you see the folders for extras and others.  From this  
point on yum.conf almost writes itself as you merely note into yum.conf  
which URL is appropriate for each section.

http://ydl.osuosl.org/yum/4.1/extras/

belongs under [extras], and so on.

One more plus regarding doing things this way, you will see for  
yourself if there is a problem with a mirror or server -- for whatever  
reason.  If you find that a server or mirror is unavailable -- just  
comment it out (use the # sign before that line) and the computer will  
ignore the instruction on that line.  Leaving the line in will remind  
you to mention it to others that this server doesn't work.  Removing  
the line is also an option but, then because you've removed it -- you  
may not remember what you removed.

Best wishes....


On Jun 17, 2006, at 5:53 AM, Bob Katz wrote:

> Hi
>      I need to update my yum conf. file as the one I had the servers  
> are
> not working  when I try to use yum I get error 404 or 403 codes what
> would be the reasons for this and how would I edit the yum file to
> restore the yum functions
>                                Thank You
> 						Bob
>
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