My root partition is on /dev/hda1 and my swap partition is on /dev/hda2.

I want to write a script that will move the swap partition to the end of the disk (or delete it and recreate it at the end of the disk) and then resize the root partition to fill the entire space in between. Script should not require any user input. Disk can be any size from 2GB to 40GB. Script will be executed while booted from SystemRescueCD.

How can I do this? I assume parted could be used in the resize step. Any help would be much appreciated. Thanks.

I assume you need to do this many times.
Yes parted would be a good choice maybe the only.
Write a simple bash script and call parted with predefined flags to handle the disk manipulation.

The swap is easy - swapoff, recreate it, mkswap, swapon.
I do a lot of fiddling with partitions. There is no way I'd use a script - too bloody dangerous if you get the maths wrong.

Yes, I need to do this many times. Basically I'm looking to do Example 1 from the GNU Parted manual (http://rush.ict.pwr.wroc.pl/docs/parted-1.4.16/USER), but without needing a user to input the start and end for the mkpartfs and the resize. The disk size can differ, so the start and end could change.

Some docs say that negative numbers in parted count from the end of the disk. Would something like the following work?

parted move 2 -125 -0
parted resize 1 0.063 -125

Would this move the swap partition in the previously cited Example to 125 megabytes from the end of the disk, and then resize the root partition to fill up the rest?