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Re: java again really

On Thu, 2008-01-03 at 09:15 -0800, Les wrote:
> On Thu, 2008-01-03 at 10:58 -0500, Matthew Saltzman wrote:
> > man alternatives
> Hi, Matthew,
> 	I have read the man page.  However, I am not sure this is simpler???
> It seems to be a tool to maintain dependency tracking for symbolic
> links.  

It's a tool for managing installation of alternative tools that
accomplish a particular purpose.  Sun Java vs. other Java is one
example.  sendmail vs. other MTA is another example.  The alternatives
system provides an automated way for packagers to permit sysadmins to
switch back and forth between tools in a (relatively) seamless way.

> The man page also repeatedly makes reference to Debian, which is
> an alternative Linux Distribution.  Given that a newbie, with some
> rudimentary knowledge (like myself or Karl) can manage symbolic links,
> and that we may or may not take on faith that a Debian tool will work
> with Fedora, how does this improve the situation?  I know that I can

It was originally written for Debian, but it's a bona fide Fedora
package, used for managing at least the two cases I listed above.

> google this, but a link could be mentioned in the man page to assist
> with this.  In other words the tool is not yet ready for many if not
> most of us until either we improve our collective knowledge, or the
> tools documentation improves to help us find our way through a minefield
> of system affecting links and link modifiers.  Personally, I think such
> a tool doing a relatively complex task needs really good documentation
> about how to read its control script, and what each command does, and a
> good example showing the effects of those commands on software updates,
> software interactions (what if a shell is calling Jave.1.4 and you
> update to Java.1.5 for example).  And where the links are stored and how
> to back rev it when software has to be removed to restore system
> functionality.
> I know the current thrust is to automate all system administration
> tasks, but when it doesn't work, who can fix it if the "trail" is
> obscured, and the author(s) of the automatic tools is no longer
> available?

The key here is that from a *user* (i.e., sysadmin) viewpoint, this tool
is pretty easy to use.  What Karl probably should have done is 

	alternatives --config java

and then selected the Sun Java alternative.  (Note, I have not installed
the java-compat package or the JPackage Sun Java to try exactly this.
F8 comes with two Javas already installed, so it's easy to extrapolate
what would happen.)

What Karl actually did is likely to have broken the alternatives links
and made his Java suite use inconsistent parts of different Javas.

Actually building a package to use alternatives is more complex, but not
relevant to the case at hand.

> Regards,
> Les H
                Matthew Saltzman

Clemson University Math Sciences
mjs AT clemson DOT edu

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