ref: 7aff811399c8b10a08ca9d95d5a9ce9bf2bfb1a6
dir: /src/lua/test/env.lua/
-- read environment variables as if they were global variables
local f=function (t,i) return os.getenv(i) end
setmetatable(getfenv(),{__index=f})
-- an example
print(a,USER,PATH)