Using the following, I still get "undefined":
var output = shell('/system/bin/curl --insecure -G https://<my server>/rest/status',false,10);
flash(output);
I've tried just about every combination of values that I can come up with. I've using single quotes and double quotes for the string, 0/1/on/off/true/false for the boolean and 0/10/20 for the integer. If I copy the actual shell command into the terminal on the phone, it works with no problems.