Incompatible upgrade - Is this workaround ok? (mysql-mmm)

[BJ Dierkes]

On Feb 24, 2010, at 9:41 PM, Chen Lei wrote:

> It's not problem to update mysql-mmm to the latest version for F13 and devel soon.
> For F11 F12 and EPEL5, you need write Scriptlet in the pre and check the startlevel of mmmd_agent and 
> mmmd_mon, then you can adapt the startlevel mmmd_agent based on mmm_agentd  and  mmmd_mon based on 
> mmm_mond. There may be some more hack to do for configuration files.
> 
> I think symlink isn't a good idea.

Thank you.  To clarify, mmmd_{agent,mon} are the names of the scripts in /usr/sbin and not the name of the init scripts (mysql-mmm-agent, mysql-mmm-monitor).  However, the sbin scripts are referenced inside the init scripts.

I suppose an alternative to creating a symlink in /usr/sbin would be to sed the init/config files to reference the new paths in %post.  My issue with that however is that I only want to make such changes if the previously installed version is < 2.1.  Is there a fedora proper way of determining the version of a package before the upgrade and only performing upgrade actions in that condition only.  Maybe something like:

%pre
# determine current version, > /tmp/somewhere

%post
# read previous version from /tmp/somewhere, if version < 2.1 then sed up init/config files for new paths


Just a thought.. I've done something like this before, but not under Fedora/EPEL.  

Additionally, an option would be to rename the new sbin scripts to have the old name...  but the old name is not standard, and it would be right to follow upstream where all their documentation references the new paths.

Thanks.

---
derks