I've got Ubuntu 10.10 installed to use my whole hard-disk, but would like to use the 130GB of free space I've got to create a new partition and do some development on Unity and Natty.
Can I use gparted to do this? If so how?
(Step 0:) Back up anything really valuable. This is a pretty tried and tested formula but things can go wrong. A power cut at the wrong moment could really ruin your day if you haven't backed up.
You can only re-partition unmounted partitions.
I have a gParted live disc ready for things like that. You can find it here: http://gparted.sourceforge.net/livecd.php
Resizing is explained in the documentation of gParted. In short (the link has some extra information and tips):
Resizing and moving a partition can be performed by a single gparted operation. To resize a partition:
One way that you can shrink partitions without losing data is by using GParted. A very good application, but be careful with it.
Edit: Boot from a live CD so you will be able to do the resizing. Install gparted with Ubuntu Software center, or any other way (synaptic etc) you prefer, if it isn't already installed.
It will ask you to authenticate when you run it, as it has access to things that can damage your installation badly. Realise that by altering partitions on your hard drive(s) you can potentially stop your system booting completely. As I said, be careful.
It will then search devices it can see and display the partitions on the first one (probably /dev/sda, if not try different devices from the pull down at the top right). You should be able to see that one of them contains your root (/) mount point. When you are sure you have the correct one (the size itself is a good indicator), right-click on that partition and choose Resize/Move (if it is greyed out, you might need to unmount it first (make sure you have booted off a live CD, and not your installed linux system). Reduce the size in the middle (New Size) edit box to what you want (make sure it's still large enough for your system's needs). Click on resize/move, then use the big green tick to apply the changes. If it reports success, then should be able to shutdown the live cd and reboot into your main system.
Edit2: I just googled a tutorial you might look at