> I'm starting to learn Ruby, and I've decided on a small web/integration
> project.  Naturally, I've got a few questions.
>
> 1) Is there a recommended framework for web-based applications?  I seem
> to recall hearing about an Enhydra XMLC clone in Ruby.
There are several different ones at http://www.ruby-lang.org/en/raa.html
From mod_ruby to more advanced stuff.
> 2) What's the best way to access (Linux) system-level calls.
>  Specifically, I'll need mount/umount, and I'll need to be able to send
> SCSI commands.
If all you need is a mount/umount, call system("mount...)
(be careful with the permissions)
> 3) Is there a package/class for JPG manipulation?
look at http://www.ruby-lang.org/en/raa.html under Graphics
maybe easiest to use Imagemagick
> 4) Is there a package/class for manipulating files on the file system
> (move, copy, delete, rename).
use rename in class File, etc.
http://www.rubycentral.com/book/ref_c_file.html

Good luck,
Armin.

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Armin Roehrl, http://www.approximity.com

Don't ask whether you can do something, but how to do it. 
-- Adele Goldberg