I ran into this useful tip that if you\'re working on files a lot and you want them to build automatically you run:
watch make
And it re-runs make every couple s
Twitter Bootstrap uses the watchr ruby gem for this.
https://github.com/twbs/bootstrap/blob/v2.3.2/Makefile
https://github.com/mynyml/watchr
After two years the watchr project seems not to be maintained anymore. Please look for another solution among the answers. Personally, if the goal is only to have a better output, i would recommend the answer from wch here