Instaled software?

Hey Chris,

Not at all. It's much more important to backup your system, particularly configuration files in /etc, before installation. Our installer isn't going to panic about stuff already being installed--but it's pretty likely to break existing configuration if your system doesn't match our defaults pretty closely.

If you don't want to backup your system, then the only safe way to install Virtualmin is via a manual installation (i.e. download the individual packages from the correct OS repository and install them)--it won't be safe to run install.sh because it will perform a large number of configuration changes. If your current system configuration is similar to our defaults, then it'll be harmless, but if you're using a different mail server, different mail spool format, different delivery agent or any mail filters, etc. things could get ugly. The manual installation leaves a lot of things undone, like spam and anti-virus filtering, SMTPD authentication, etc., that'll have to be setup manually (not much to it, as Virtualmin itself does a lot of the work for you, but there's a few one-time changes needed).

Also, if you've installed your packages from some source other than the OS provided packages, things could get ugly.

BTW-Our defaults (that matter to install.sh) are:

Postfix
Maildir storage in ~/Maildir
Procmail for delivery
Domain homes in /home

If you're doing that, and you aren't using packages from a source other than the OS (and Webmin/Usermin from the packages offered at webmin.com), then install.sh should be able to upgrade you just fine. It's better tested for such upgrades on Fedora and CentOS. I suggest caution on all of the other supported systems. (And please have a good recent backup, in any case.)