[Yum] --allow-downgrade - how does it work? still having problems...

[Troy Dawson]

Seth Vidal wrote:
> On Thu, 2008-09-18 at 22:55 +0200, Nikola Ciprich wrote:
>> Hello everybody,
>> some time ago, I asked here for help, because I can't get allowdowngrade plugin
>> working. We didn't come to any conclusion, and I didn't have time to play with
>> it anymore, but now I got back to it, and I'd like to ask for bit of explanation.
>> I did a bit of exploring, and I'm a bit confused. It seems that allowdowngrade adds
>> hooks to postresolve, but if I try to install package, yum just doesn't get there
>> at all, so plugin can't really change anything.
>> It seems that it ends in yum/__init__.py, after line 2392 (install method):
>>
>>             # make sure we don't have a name.arch of this already installed
>>             # if so pass it to update b/c it should be able to figure it out
>>             if self.rpmdb.contains(name=po.name, arch=po.arch) and not self.allowedMultipleInstalls(po):
>>                 if not self.tsInfo.getMembersWithState(po.pkgtup, TS_REMOVE_STATES):
>>                     self.verbose_logger.warning(_('Package matching %s already installed. Checking for update.')
>>                     txmbrs = self.update(po=po)
>>                     tx_return.extend(txmbrs)
>>                     continue
>>
>> self.update(po=po) returns empty list, which causes package to be skipped. Is this intended behaviour?
>> Should I be looking elsewhere?
>> I'm using latest yum and yum-allowdowngrade
>> Any ideas?
>> thanks a lot in advance!
>> with best regards
> 
> Nope, I think you're on the right path. Making sure allowdowngrade
> semi-behaves is on my list to fix before 3.2.20 comes out.
> 
> If you can fix it w/o breaking more things please send a patch you may
> have.
> 
> -sv
> 

Hi All,
I'm looking back and it looks like I never got back with the syntax of 
allow-downgrade.

I don't know about 3.2.20, but in 3.2.8 it is working, but the syntax is a 
little different than expected.

Make sure you have the allowdowngrade plugin installed. Also make sure that the 
downgraded rpm is in your yum repository.
The syntax is

yum --allow-downgrade install <rpm name in special format>

The special format is gotten by doing
rpm -qp --qf "%|epoch?{%{epoch}}:{0}|:%{name}-%{version}-%{release}.%{arch}\n" 
<rpm>

So a package like firefox-3.0-0.beta5.6.el5.i386.rpm comes out like 
0:firefox-3.0-0.beta5.6.el5.i386

Troy
p.s. I'm about ready to post of plugin called versionfix which was originally 
based on allow-downgrade, which is why I saw this.
-- 
__________________________________________________
Troy Dawson  dawson at fnal.gov  (630)840-6468
Fermilab  ComputingDivision/LCSI/CSI DSS Group
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