read a file from cucumber.yml

cucumber.yml

common: SCREENSHOT_PATH=./cucumber-screenshots/ -f 'Slowhandcuke::Formatter' OS=ios5
rerun_out: -f rerun -o rerun.txt
no_launch: EMBED=1 NO_LAUNCH=1
ipad: DEVICE=ipad -p common -p no_launch 
iphone: DEVICE=iphone -p common -p no_launch

<%
pluto_ip = IO.read("#{ENV['HOME']}/.lesspainful/devices/pluto")
neptune_ip = IO.read("#{ENV['HOME']}/.lesspainful/devices/neptune")
%>

default: -p common -p rerun_out -p no_launch
launch: -p common -p rerun_out
rerun: -p common -p no_launch @rerun.txt
wip: -p common -p rerun_out -p no_launch --tags @wip:3 --wip
pluto: -f rerun -o rerun-pluto.txt -p ipad DEVICE_ENDPOINT=<%= pluto_ip %>
neptune: -f rerun -o rerun-neptune.txt -p iphone DEVICE_ENDPOINT=<%= neptune_ip %>

works now