How to ease re-install "upgrades"?

[James Wilkinson]

Mike Bartman wrote:
> Speaking of which, what tricks do people have for easing an "upgrade"
> that's done by installing a fresh copy of a newer system?  Upgrade installs
> often only work for adjacent, or almost adjacent, versions...
<snip>
> ...but making sure you didn't miss
> anything before you wipe the old setup is nice.  Having to dig it out of
> backups takes time.
> 
> I've got /home on a separate partition that I don't need to mess with when
> re-installing (it's worked for a couple of RHL upgrades so far anyway), so
> the stuff that needs carrying over is mostly system setups (DNS configs,
> sendmail setup, user account info, etc.).  It can be saved in the /home
> tree for reference in setting up the new system once it's up and running,
> but how to get all the required stuff, without any critical omissions, is a
> potential problem.  

Practically all of that lives in /etc, which should not be large. Copy
all of /etc into your home directory before upgrading.

Consider what you've installed yourself: make a rule that it goes into
/usr/local or opt. You could make /opt a symlink to /usr/local/opt, and
/usr/local a separate filesystem: that way the installer doesn't need
to touch it.

Make a policy decision about where your system scripts go.

Make sure /var/spool/mqueue and /var/spool/mail (or equivalents) are
empty.

HTH,

James.

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