ref: 7060937f97b2c6a7c41b90a2f34a3dd3a14dae0d
dir: /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)