ref: efe0b2a1f4f0ddd412a63b7dfa5445d795629d64
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)