Package Manager Question

[Rick Stevens]

On 03/16/2010 11:12 AM, Karl Pearson wrote:
>
>
>
> On Tue, March 16, 2010 11:26 am, Rick Stevens wrote:
>> On 03/15/2010 06:44 PM, Karl Pearson wrote:
>>> Hi all,
>>>
>>> I use Fedora on my server (email, web, etc.) and have been using Linux
>>> Mint on my desktop and laptop.
>>>
>>> I've noticed something that has caused me to ask this question. First,
>>> what I've noticed:
>>>
>>> When I update a package using that package's 'Check For Update' feature
>>> on
>>> the Help menu (Virtualbox is a prime example), Linux Mint, which uses
>>> dpkg, the debian package manager, automatically updates the repository
>>> indexes on my PC and shows the package installed when I run Synaptic.
>>>
>>> I don't remember YumX ever doing this, or any other RPM front-end, or
>>> rpm
>>> itself from the commandline. If I didn't install a package from the
>>> repositories, rpm didn't know it was there.
>>>
>>> Do you know if this has been "fixed" (if it's actually broken)?
>>>
>>> I'm going to install a new server with CentOS soon, and have toyed with
>>> the idea of using it as my workstation OS as well.
>>
>> What you're experiencing is standard yum practice.  It doesn't know
>> about repos unless it has a config for it.
>>
>> A config is a stanza inside a file in the /etc/yum.repos.d directory.
>> A stanza starts with the name of the repo in square brackets, e.g.:
>>
>> 	[fedora]
>>
>> Following that is a number of things which control how yum interacts
>> with the repo.  One of the most important is:
>>
>> 	enabled=[0|1]
>>
>> If the stanza has "enabled=1", then yum will check and/or use it. If
>> it has "enabled=0", then it's ignored.  Default is "enabled=0" for any
>> stanza that doesn't have it explicitly defined.
>>
>> You can force a disabled repo ("enabled=0") to be scanned by adding:
>>
>> 	--enablerepo=<repo-name-glob>
>>
>> on the yum command line before any commands.  Example:
>>
>> 	yum --enablerepo=livna update
>>
>> The standard way of checking for updates interactively is by doing a
>>
>> 	yum update
>>
>> It'll tell you if there are things that need updating.  If there are,
>> it'll ask you if you want to do the update now.  If you way "yes", the
>> the update process begins.
>>
>> If you want just want to check for updates non-interactively (e.g. in a
>> script), use:
>>
>> 	yum check-update
>>
>> which will return a return code of 100 if there are things that need
>> updating, 1 if an error occurs and 0 if there are no updates.
>
> I've been using yum for years, and like it, but that wasn't my question.
> I'm wondering if yum has the same capability (yet) that dpkg has of
> knowing what's been installed, even if it's done through the package's own
> update process, like Virtualbox or any other package that has a [Help>
> About>  CheckForUpdates] feature.

No.  yum uses rpm's database to identify what's already installed and
the differences between that and data it finds in the repos that are in
its config for things that are "available".

Ideally packages should cooperate with rpm when they install, but they
usually don't.  One could run an auxiliary database update I suppose,
but most tarball installs don't have a convenient "here's the list of
files I'm installing" that the scanner could use to identify what file
belongs to what package.  Indeed, a tarball install stretches the
concept of "package" quite a bit.
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- Rick Stevens, Systems Engineer, C2 Hosting          ricks at nerd.com -
- AIM/Skype: therps2        ICQ: 22643734            Yahoo: origrps2 -
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-        Hard work has a future payoff. Laziness pays off now.       -
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