Sorry to dig out an old thread...but I've been trying to set my Nest to AWAY mode based on a radius from the house (geofence), today I decided to just get it figured out!!
So from the linux/mac command line you want to pull a variable from the ISY??
1 - log into the isy and figure out if the variable is a state or integer, also note the number of the variable. In this example, I'm using my state variable #4.
2 - from your browser use http://192.168.1.30/rest/vars/get/2/4/ (insertyour isy's IP, leave the path alone, 1=integer 2=state, replace my 4 with the variable number) keep playing with this until you get a xml formatted response that looks like this:
<var type="2" id="4">
<init>2</init>
<val>1</val>
<ts>20150305 18:24:12</ts>
</var>
3 - the "val" tag is all you want, so from command line, just run this (change the IP, 2, and 4 to match the URL you found in step 2):
echo `wget -qO- test.xml --user=YOURUSERNAME --password=YOURPASSWORD http://192.168.1.xx/rest/vars/get/2/4/`| cut -d'>' -f6 | cut -d'<' -f1
(the wget is the command line pull for a web request, normally it would save it to a file but the -qO- makes it quiet and echo it out, but then the two cut command trim the xml so that you just end up with your desired variable)
Why would you want to use: from the command line, you can just drop the line any time and get the value of that variable. For me, I am using the mobilinc app to set the variable based on me being a mile from my home - my results are a 0 (away) or 1 (home or close to home). So then I am going to use the rest of my script to set the status of my NEST thermostat to Home or Away (save $$). I can also shut off all the lights in the house (save $$), I can get a text that the garage is open (save my grill!!)... imagination is the limit here.
Thanks to elvisimprsntr for the interrogation script (https://gist.github.com/elvisimprsntr/4052516) that sped up the digging.
PS - big fan of elvisimprsntr, loved loved loved the work on the RaspPi SiriProxy - so wish we had it back. Fingers crossed that the API for the Amazon Echo is worth the wait!! I saw your work on the Homekit stuff, I'll look into it to see the state of /art/.