Around 1995 I built some configuration management software based on M4, because I thought it was cool! Actually, it didn't do much in the way of management, but

Around 1995 I built some configuration management software based on M4, because I thought it was cool! Actually, it didn't do much in the way of management, but it did allow the ISP I was working for at the time to provision a customer gateway in a single step. Saved me a lot of error-prone and rather boring hand-editing of configuration files... (and probably saved the company some money, who knows)