Hello,
GDT is Windows only at the moment. You can run GDT inside of a VM in Linux, but that still requires Windows in the VM.
While I've not tested GDT in any VMs, I have had people tell me that they've had no problems doing so.
Right now I have no intentions on creating a Linux version. My next endeavor (when time permits) will be an OSX version. Later, if I have time, I will consider a Linux version, but for now, there's simply not enough demand for Linux software. Sorry. :(
I hope that helps somewhat.
Ryan