如何在Linux下生成系统范围的唯一ID

I'm working on a multiprocess Linux system and need to generate unique IDs. Security is not a consideration, so an ID generator that starts at zero and counts up would be fine. Also it's just within a local machine, no network involved. Obviously it's not hard to implement this, but I was just wondering if there was anything already provided (preferably lightweight).I'm working on a multiprocess Linux system and