There is already a plugin out there to control the Silhouette through Inkscape, but we had trouble finding directions for Ubuntu.
This Instructable shows tested steps that can get a Silhouette working using Inkscape software on Ubuntu and RaspberryPi.
First, you'll need Inkscape:
This is part of a Silhouette Portrait Group Build with Instructables at Knox Makers.
Step 1: Get the Plugin
We detailed steps here:
Thanks to Doug and Jondale for throwing together succinct technical steps here.
Step 2: Open Inkscape
After you have committed the changes to the lp group and Inkscape by logging out and logging back in, now open Inkscape.
Get a simple design ready to test out.
Turn on your Silhouette.
Using your SVG image, go to Extensions >> Export >> Send to Silhouette.
There are some settings to try out, but just go ahead and go with the default settings to see if Inkscape can control your Silhouette now.
Step 3: Enjoy!
If all went well, you should now be able to control your Silhouette using Inkscape.